<s>
Bitcoin	B-General_Concept
(	O
abbreviation	O
:	O
BTC	O
or	O
XBT	O
;	O
sign	O
:	O
₿	B-Protocol
)	O
is	O
a	O
protocol	O
which	O
implements	O
a	O
highly	O
available	O
,	O
public	O
,	O
permanent	O
,	O
and	O
decentralized	O
ledger	B-Language
.	O
</s>
<s>
In	O
order	O
to	O
add	O
to	O
the	O
ledger	B-Language
,	O
a	O
user	O
must	O
prove	O
they	O
control	O
an	O
entry	O
in	O
the	O
ledger	B-Language
.	O
</s>
<s>
The	O
protocol	O
specifies	O
that	O
the	O
entry	O
indicates	O
an	O
amount	O
of	O
a	O
token	O
,	O
bitcoin	B-General_Concept
with	O
a	O
minuscule	O
b	O
.	O
</s>
<s>
The	O
user	O
can	O
update	O
the	O
ledger	B-Language
,	O
assigning	O
some	O
of	O
their	O
bitcoin	B-General_Concept
to	O
another	O
entry	O
in	O
the	O
ledger	B-Language
.	O
</s>
<s>
Bitcoin	B-General_Concept
transactions	O
are	O
verified	O
by	O
network	B-Protocol
nodes	I-Protocol
through	O
cryptography	O
and	O
recorded	O
in	O
a	O
public	O
distributed	O
ledger	B-Language
called	O
a	O
blockchain	B-Application
.	O
</s>
<s>
The	O
currency	O
began	O
use	O
in	O
2009	O
,	O
when	O
its	O
implementation	O
was	O
released	O
as	O
open-source	B-Application
software	I-Application
.	O
</s>
<s>
The	O
word	O
"	O
bitcoin	B-General_Concept
"	O
was	O
defined	O
in	O
a	O
white	O
paper	O
published	O
on	O
October	O
31	O
,	O
2008	O
.	O
</s>
<s>
The	O
Library	O
of	O
Congress	O
reports	O
that	O
,	O
as	O
of	O
November	O
2021	O
,	O
nine	O
countries	O
have	O
fully	O
banned	O
bitcoin	B-General_Concept
use	O
,	O
and	O
a	O
further	O
forty-two	O
have	O
implicitly	O
banned	O
it	O
.	O
</s>
<s>
A	O
few	O
governments	O
have	O
used	O
bitcoin	B-General_Concept
in	O
some	O
capacity	O
.	O
</s>
<s>
El	O
Salvador	O
has	O
adopted	O
Bitcoin	B-General_Concept
as	O
legal	O
tender	O
,	O
although	O
use	O
by	O
merchants	O
remains	O
low	O
.	O
</s>
<s>
Iran	O
has	O
used	O
bitcoin	B-General_Concept
to	O
bypass	O
sanctions	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
has	O
been	O
described	O
as	O
an	O
economic	O
bubble	O
by	O
at	O
least	O
eight	O
recipients	O
of	O
the	O
Nobel	O
Memorial	O
Prize	O
in	O
Economic	O
Sciences	O
.	O
</s>
<s>
The	O
environmental	B-General_Concept
effects	I-General_Concept
of	I-General_Concept
bitcoin	I-General_Concept
are	O
substantial	O
.	O
</s>
<s>
Its	O
proof-of-work	O
algorithm	O
for	O
bitcoin	B-General_Concept
mining	O
is	O
designed	O
to	O
be	O
computationally	O
difficult	O
,	O
which	O
requires	O
the	O
consumption	O
of	O
increasing	O
quantities	O
of	O
electricity	O
,	O
the	O
generation	O
of	O
which	O
has	O
contributed	O
to	O
climate	O
change	O
.	O
</s>
<s>
According	O
to	O
the	O
University	O
of	O
Cambridge	O
,	O
bitcoin	B-General_Concept
has	O
emitted	O
an	O
estimated	O
200	O
million	O
tonnes	O
of	O
carbon	O
dioxide	O
since	O
its	O
launch	O
,	O
or	O
about	O
0.04	O
%	O
of	O
all	O
carbon	O
dioxide	O
released	O
since	O
2009	O
.	O
</s>
<s>
The	O
unit	O
of	O
account	O
of	O
the	O
bitcoin	B-General_Concept
system	O
is	O
the	O
bitcoin	B-General_Concept
.	O
</s>
<s>
Currency	O
codes	O
for	O
representing	O
bitcoin	B-General_Concept
are	O
BTC	O
and	O
XBT	O
.	O
</s>
<s>
Its	O
Unicode	O
character	O
is	O
₿	B-Protocol
.	O
</s>
<s>
One	O
bitcoin	B-General_Concept
is	O
divisible	O
to	O
eight	O
decimal	O
places	O
.	O
</s>
<s>
Units	O
for	O
smaller	O
amounts	O
of	O
bitcoin	B-General_Concept
are	O
the	O
millibitcoin	O
(	O
mBTC	B-Protocol
)	O
,	O
equal	O
to	O
bitcoin	B-General_Concept
,	O
and	O
the	O
satoshi	O
(	O
sat	O
)	O
,	O
which	O
is	O
the	O
smallest	O
possible	O
division	O
,	O
and	O
named	O
in	O
homage	O
to	O
bitcoin	B-General_Concept
's	O
creator	O
,	O
representing	O
(	O
one	O
hundred	O
millionth	O
)	O
bitcoin	B-General_Concept
.	O
</s>
<s>
100,000	O
satoshis	B-Protocol
are	O
one	O
mBTC	B-Protocol
.	O
</s>
<s>
The	O
bitcoin	B-General_Concept
blockchain	B-Application
is	O
a	O
public	O
ledger	B-Language
that	O
records	O
bitcoin	B-General_Concept
transactions	O
.	O
</s>
<s>
It	O
is	O
implemented	O
as	O
a	O
chain	O
of	O
blocks	O
,	O
each	O
block	O
containing	O
a	O
cryptographic	B-Algorithm
hash	I-Algorithm
of	O
the	O
previous	O
block	O
up	O
to	O
the	O
genesis	O
block	O
in	O
the	O
chain	O
.	O
</s>
<s>
A	O
network	B-General_Concept
of	O
communicating	O
nodes	B-Protocol
running	O
bitcoin	B-General_Concept
software	O
maintains	O
the	O
blockchain	B-Application
.	O
</s>
<s>
Transactions	O
of	O
the	O
form	O
payer	O
X	O
sends	O
Y	O
bitcoins	B-General_Concept
to	O
payee	O
Z	O
are	O
broadcast	B-Operating_System
to	O
this	O
network	B-General_Concept
using	O
readily	O
available	O
software	O
applications	O
.	O
</s>
<s>
Network	B-Protocol
nodes	I-Protocol
can	O
validate	O
transactions	O
,	O
add	O
them	O
to	O
their	O
copy	O
of	O
the	O
ledger	B-Language
,	O
and	O
then	O
broadcast	B-Operating_System
these	O
ledger	B-Language
additions	O
to	O
other	O
nodes	B-Protocol
.	O
</s>
<s>
To	O
achieve	O
independent	O
verification	O
of	O
the	O
chain	O
of	O
ownership	O
,	O
each	O
network	B-Protocol
node	I-Protocol
stores	O
its	O
own	O
copy	O
of	O
the	O
blockchain	B-Application
.	O
</s>
<s>
At	O
varying	O
intervals	O
of	O
time	O
averaging	O
to	O
every	O
10	O
minutes	O
,	O
a	O
new	O
group	O
of	O
accepted	O
transactions	O
,	O
called	O
a	O
block	O
,	O
is	O
created	O
,	O
added	O
to	O
the	O
blockchain	B-Application
,	O
and	O
quickly	O
published	O
to	O
all	O
nodes	B-Protocol
,	O
without	O
requiring	O
central	O
oversight	O
.	O
</s>
<s>
This	O
allows	O
bitcoin	B-General_Concept
software	O
to	O
determine	O
when	O
a	O
particular	O
bitcoin	B-General_Concept
was	O
spent	O
,	O
which	O
is	O
needed	O
to	O
prevent	O
double-spending	B-Operating_System
.	O
</s>
<s>
A	O
conventional	O
ledger	B-Language
records	O
the	O
transfers	O
of	O
actual	O
bills	O
or	O
promissory	O
notes	O
that	O
exist	O
apart	O
from	O
it	O
,	O
but	O
as	O
a	O
digital	O
ledger	B-Language
,	O
bitcoins	B-General_Concept
only	O
exist	O
by	O
virtue	O
of	O
the	O
blockchain	B-Application
;	O
they	O
are	O
represented	O
by	O
the	O
unspent	B-Protocol
outputs	I-Protocol
of	I-Protocol
transactions	I-Protocol
.	O
</s>
<s>
Individual	O
blocks	O
,	O
public	O
addresses	O
,	O
and	O
transactions	O
within	O
blocks	O
can	O
be	O
examined	O
using	O
a	O
blockchain	B-Application
explorer	O
.	O
</s>
<s>
Transactions	O
are	O
defined	O
using	O
a	O
Forth-like	O
scripting	O
language	O
.	O
</s>
<s>
When	O
a	O
user	O
sends	O
bitcoins	B-General_Concept
,	O
the	O
user	O
designates	O
each	O
address	O
and	O
the	O
amount	O
of	O
bitcoin	B-General_Concept
being	O
sent	O
to	O
that	O
address	O
in	O
an	O
output	O
.	O
</s>
<s>
To	O
prevent	O
double	B-Operating_System
spending	I-Operating_System
,	O
each	O
input	O
must	O
refer	O
to	O
a	O
previous	O
unspent	O
output	O
in	O
the	O
blockchain	B-Application
.	O
</s>
<s>
Since	O
transactions	O
can	O
have	O
multiple	O
outputs	O
,	O
users	O
can	O
send	O
bitcoins	B-General_Concept
to	O
multiple	O
recipients	O
in	O
one	O
transaction	O
.	O
</s>
<s>
Any	O
input	O
satoshis	B-Protocol
not	O
accounted	O
for	O
in	O
the	O
transaction	O
outputs	O
become	O
the	O
transaction	O
fee	O
.	O
</s>
<s>
These	O
fees	O
are	O
generally	O
measured	O
in	O
satoshis	B-Protocol
per	O
byte	O
(	O
sat/b	O
)	O
.	O
</s>
<s>
The	O
blocks	O
in	O
the	O
blockchain	B-Application
were	O
originally	O
limited	O
to	O
32	O
megabytes	O
in	O
size	O
.	O
</s>
<s>
Eventually	O
,	O
the	O
block	O
size	O
limit	O
of	O
one	O
megabyte	O
created	O
problems	B-Protocol
for	O
transaction	O
processing	O
,	O
such	O
as	O
increasing	O
transaction	O
fees	O
and	O
delayed	O
processing	O
of	O
transactions	O
.	O
</s>
<s>
Andreas	O
Antonopoulos	O
has	O
stated	O
Lightning	B-Protocol
Network	I-Protocol
is	O
a	O
potential	O
scaling	O
solution	O
and	O
referred	O
to	O
lightning	O
as	O
a	O
second-layer	O
routing	O
network	B-General_Concept
.	O
</s>
<s>
In	O
the	O
blockchain	B-Application
,	O
bitcoins	B-General_Concept
are	O
registered	O
to	O
bitcoin	B-General_Concept
addresses	O
.	O
</s>
<s>
Creating	O
a	O
bitcoin	B-General_Concept
address	O
requires	O
nothing	O
more	O
than	O
picking	O
a	O
random	O
valid	O
private	B-Application
key	I-Application
and	O
computing	O
the	O
corresponding	O
bitcoin	B-General_Concept
address	O
.	O
</s>
<s>
But	O
the	O
reverse	O
,	O
computing	O
the	O
private	B-Application
key	I-Application
of	O
a	O
given	O
bitcoin	B-General_Concept
address	O
,	O
is	O
practically	O
unfeasible	O
.	O
</s>
<s>
Users	O
can	O
tell	O
others	O
or	O
make	O
public	O
a	O
bitcoin	B-General_Concept
address	O
without	O
compromising	O
its	O
corresponding	O
private	B-Application
key	I-Application
.	O
</s>
<s>
Moreover	O
,	O
the	O
number	O
of	O
valid	O
private	B-Application
keys	I-Application
is	O
so	O
vast	O
that	O
it	O
is	O
extremely	O
unlikely	O
someone	O
will	O
compute	O
a	O
key	B-Application
pair	I-Application
that	O
is	O
already	O
in	O
use	O
and	O
has	O
funds	O
.	O
</s>
<s>
The	O
vast	O
number	O
of	O
valid	O
private	B-Application
keys	I-Application
makes	O
it	O
unfeasible	O
that	O
brute	O
force	O
could	O
be	O
used	O
to	O
compromise	O
a	O
private	B-Application
key	I-Application
.	O
</s>
<s>
To	O
be	O
able	O
to	O
spend	O
their	O
bitcoins	B-General_Concept
,	O
the	O
owner	O
must	O
know	O
the	O
corresponding	O
private	B-Application
key	I-Application
and	O
digitally	O
sign	O
the	O
transaction	O
.	O
</s>
<s>
The	O
network	B-General_Concept
verifies	O
the	O
signature	O
using	O
the	O
public	B-Application
key	I-Application
;	O
the	O
private	B-Application
key	I-Application
is	O
never	O
revealed	O
.	O
</s>
<s>
If	O
the	O
private	B-Application
key	I-Application
is	O
lost	O
,	O
the	O
bitcoin	B-General_Concept
network	I-General_Concept
will	O
not	O
recognize	O
any	O
other	O
evidence	O
of	O
ownership	O
;	O
the	O
coins	O
are	O
then	O
unusable	O
,	O
and	O
effectively	O
lost	O
.	O
</s>
<s>
For	O
example	O
,	O
in	O
2013	O
one	O
user	O
claimed	O
to	O
have	O
lost	O
₿7	O
,	O
500	O
,	O
worth	O
$7.5	O
million	O
at	O
the	O
time	O
,	O
when	O
he	O
accidentally	O
discarded	O
a	O
hard	O
drive	O
containing	O
his	O
private	B-Application
key	I-Application
.	O
</s>
<s>
About	O
20%	O
of	O
all	O
bitcoins	B-General_Concept
are	O
believed	O
to	O
be	O
lostthey	O
would	O
have	O
had	O
a	O
market	O
value	O
of	O
about	O
$20	O
billion	O
at	O
July	O
2018	O
prices	O
.	O
</s>
<s>
To	O
ensure	O
the	O
security	O
of	O
bitcoins	B-General_Concept
,	O
the	O
private	B-Application
key	I-Application
must	O
be	O
kept	O
secret	O
.	O
</s>
<s>
If	O
the	O
private	B-Application
key	I-Application
is	O
revealed	O
to	O
a	O
third	O
party	O
,	O
e.g.	O
</s>
<s>
through	O
a	O
data	O
breach	O
,	O
the	O
third	O
party	O
can	O
use	O
it	O
to	O
steal	O
any	O
associated	O
bitcoins	B-General_Concept
.	O
</s>
<s>
Regarding	O
ownership	O
distribution	O
,	O
as	O
of	O
28	O
December	O
2022	O
,	O
9.62	O
%	O
of	O
bitcoin	B-General_Concept
addresses	O
own	O
98.51	O
%	O
of	O
all	O
bitcoins	B-General_Concept
ever	O
mined	O
.	O
</s>
<s>
The	O
largest	O
of	O
these	O
addresses	O
are	O
thought	O
to	O
belong	O
to	O
exchanges	O
,	O
which	O
are	O
keeping	O
their	O
bitcoin	B-General_Concept
in	O
cold	O
storage	O
.	O
</s>
<s>
Miners	O
keep	O
the	O
blockchain	B-Application
consistent	O
,	O
complete	O
,	O
and	O
unalterable	O
by	O
repeatedly	O
grouping	O
newly	O
broadcast	B-Operating_System
transactions	O
into	O
a	O
block	O
,	O
which	O
is	O
then	O
broadcast	B-Operating_System
to	O
the	O
network	B-General_Concept
and	O
verified	O
by	O
recipient	O
nodes	B-Protocol
.	O
</s>
<s>
Each	O
block	O
contains	O
a	O
SHA-256	B-Algorithm
cryptographic	B-Algorithm
hash	I-Algorithm
of	O
the	O
previous	O
block	O
,	O
thus	O
linking	O
it	O
to	O
the	O
previous	O
block	O
and	O
giving	O
the	O
blockchain	B-Application
its	O
name	O
.	O
</s>
<s>
To	O
be	O
accepted	O
by	O
the	O
rest	O
of	O
the	O
network	B-General_Concept
,	O
a	O
new	O
block	O
must	O
contain	O
a	O
proof-of-work	O
(	O
PoW	O
)	O
.	O
</s>
<s>
The	O
PoW	O
requires	O
miners	O
to	O
find	O
a	O
number	O
called	O
a	O
nonce	O
(	O
a	O
number	O
used	O
just	O
once	O
)	O
,	O
such	O
that	O
when	O
the	O
block	O
content	O
is	O
hashed	B-Algorithm
along	O
with	O
the	O
nonce	O
,	O
the	O
result	O
is	O
numerically	O
smaller	O
than	O
the	O
network	B-General_Concept
's	O
difficulty	O
target	O
.	O
</s>
<s>
This	O
PoW	O
is	O
easy	O
for	O
any	O
node	B-Protocol
in	O
the	O
network	B-General_Concept
to	O
verify	O
,	O
but	O
extremely	O
time-consuming	O
to	O
generate	O
.	O
</s>
<s>
Because	O
the	O
difficulty	O
target	O
is	O
extremely	O
small	O
compared	O
to	O
a	O
typical	O
SHA-256	B-Algorithm
hash	B-Error_Name
,	O
block	O
hashes	B-Error_Name
have	O
many	O
leading	O
zeros	O
as	O
can	O
be	O
seen	O
in	O
this	O
example	O
block	O
hash	B-Error_Name
:	O
</s>
<s>
Every	O
2,016	O
blocks	O
(	O
approximately	O
14	O
days	O
given	O
roughly	O
10	O
minutes	O
per	O
block	O
)	O
,	O
nodes	B-Protocol
deterministically	B-General_Concept
adjust	I-General_Concept
the	O
difficulty	O
target	O
based	O
on	O
the	O
recent	O
rate	O
of	O
block	O
generation	O
,	O
with	O
the	O
aim	O
of	O
keeping	O
the	O
average	O
time	O
between	O
new	O
blocks	O
at	O
ten	O
minutes	O
.	O
</s>
<s>
In	O
this	O
way	O
the	O
system	O
automatically	O
adapts	O
to	O
the	O
total	O
amount	O
of	O
mining	O
power	O
on	O
the	O
network	B-General_Concept
.	O
</s>
<s>
,	O
it	O
takes	O
on	O
average	O
122	O
sextillion	O
(	O
122	O
thousand	O
billion	O
billion	O
)	O
attempts	O
to	O
generate	O
a	O
block	O
hash	B-Error_Name
smaller	O
than	O
the	O
difficulty	O
target	O
.	O
</s>
<s>
The	O
proof-of-work	O
system	O
,	O
alongside	O
the	O
chaining	O
of	O
blocks	O
,	O
makes	O
modifications	O
to	O
the	O
blockchain	B-Application
extremely	O
hard	O
,	O
as	O
an	O
attacker	O
must	O
modify	O
all	O
subsequent	O
blocks	O
in	O
order	O
for	O
the	O
modifications	O
of	O
one	O
block	O
to	O
be	O
accepted	O
.	O
</s>
<s>
The	O
vast	O
majority	O
of	O
mining	O
power	O
is	O
grouped	O
together	O
in	O
mining	B-Protocol
pools	I-Protocol
to	O
reduce	O
variance	O
in	O
miner	O
income	O
.	O
</s>
<s>
In	O
a	O
mining	B-Protocol
pool	I-Protocol
,	O
all	O
participating	O
miners	O
get	O
paid	O
every	O
time	O
any	O
participant	O
generates	O
a	O
block	O
.	O
</s>
<s>
Every	O
10	O
minutes	O
,	O
the	O
successful	O
miner	O
finding	O
the	O
new	O
block	O
is	O
allowed	O
by	O
the	O
rest	O
of	O
the	O
network	B-General_Concept
to	O
collect	O
for	O
themselves	O
all	O
transaction	O
fees	O
from	O
transactions	O
they	O
included	O
in	O
the	O
block	O
,	O
as	O
well	O
as	O
a	O
predetermined	O
reward	O
of	O
newly	O
created	O
bitcoins	B-General_Concept
.	O
</s>
<s>
,	O
this	O
reward	O
is	O
₿	O
6.25	O
in	O
newly	O
created	O
bitcoins	B-General_Concept
per	O
block	O
.	O
</s>
<s>
All	O
bitcoins	B-General_Concept
in	O
existence	O
have	O
been	O
created	O
through	O
this	O
type	O
of	O
transaction	O
.	O
</s>
<s>
The	B-General_Concept
bitcoin	I-General_Concept
protocol	I-General_Concept
specifies	O
that	O
the	O
reward	O
for	O
adding	O
a	O
block	O
will	O
be	O
reduced	O
by	O
half	O
every	O
210,000	O
blocks	O
(	O
approximately	O
every	O
four	O
years	O
)	O
,	O
until	O
₿21million	O
are	O
generated	O
.	O
</s>
<s>
The	O
last	O
new	O
bitcoin	B-General_Concept
will	O
be	O
generated	O
around	O
the	O
year	O
2140	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
is	O
decentralized	O
thus	O
:	O
</s>
<s>
Bitcoin	B-General_Concept
does	O
not	O
have	O
a	O
central	O
authority	O
.	O
</s>
<s>
The	O
bitcoin	B-General_Concept
network	I-General_Concept
is	O
peer-to-peer	O
,	O
without	O
central	O
servers	O
.	O
</s>
<s>
The	O
network	B-General_Concept
also	O
has	O
no	O
central	O
storage	O
;	O
the	O
bitcoin	B-General_Concept
ledger	B-Language
is	O
distributed	O
.	O
</s>
<s>
The	O
ledger	B-Language
is	O
public	O
;	O
anybody	O
can	O
store	O
it	O
on	O
a	O
computer	O
.	O
</s>
<s>
There	O
is	O
no	O
single	O
administrator	O
;	O
the	O
ledger	B-Language
is	O
maintained	O
by	O
a	O
network	B-General_Concept
of	O
equally	O
privileged	O
miners	O
.	O
</s>
<s>
The	O
additions	O
to	O
the	O
ledger	B-Language
are	O
maintained	O
through	O
competition	O
.	O
</s>
<s>
Until	O
a	O
new	O
block	O
is	O
added	O
to	O
the	O
ledger	B-Language
,	O
it	O
is	O
not	O
known	O
which	O
miner	O
will	O
create	O
the	O
block	O
.	O
</s>
<s>
The	O
issuance	O
of	O
bitcoins	B-General_Concept
is	O
decentralized	O
.	O
</s>
<s>
Anybody	O
can	O
create	O
a	O
new	O
bitcoin	B-General_Concept
address	O
(	O
a	O
bitcoin	B-General_Concept
counterpart	O
of	O
a	O
bank	O
account	O
)	O
without	O
needing	O
any	O
approval	O
.	O
</s>
<s>
Anybody	O
can	O
send	O
a	O
transaction	O
to	O
the	O
network	B-General_Concept
without	O
needing	O
any	O
approval	O
;	O
the	O
network	B-General_Concept
merely	O
confirms	O
that	O
the	O
transaction	O
is	O
legitimate	O
.	O
</s>
<s>
Although	O
bitcoin	B-General_Concept
can	O
be	O
sent	O
directly	O
from	O
user	O
to	O
user	O
,	O
in	O
practice	O
intermediaries	O
are	O
widely	O
used	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
miners	O
join	O
large	O
mining	B-Protocol
pools	I-Protocol
to	O
minimize	O
the	O
variance	O
of	O
their	O
income	O
.	O
</s>
<s>
Because	O
transactions	O
on	O
the	O
network	B-General_Concept
are	O
confirmed	O
by	O
miners	O
,	O
decentralization	O
of	O
the	O
network	B-General_Concept
requires	O
that	O
no	O
single	O
miner	O
or	O
mining	B-Protocol
pool	I-Protocol
obtains	O
51%	O
of	O
the	O
hashing	O
power	O
,	O
which	O
would	O
allow	O
them	O
to	O
double-spend	O
coins	O
,	O
prevent	O
certain	O
transactions	O
from	O
being	O
verified	O
and	O
prevent	O
other	O
miners	O
from	O
earning	O
income	O
.	O
</s>
<s>
just	O
six	O
mining	B-Protocol
pools	I-Protocol
controlled	O
75%	O
of	O
overall	O
bitcoin	B-General_Concept
hashing	O
power	O
.	O
</s>
<s>
In	O
2014	O
mining	B-Protocol
pool	I-Protocol
Ghash.io	O
obtained	O
51%	O
hashing	O
power	O
which	O
raised	O
significant	O
controversies	O
about	O
the	O
safety	O
of	O
the	O
network	B-General_Concept
.	O
</s>
<s>
The	O
pool	O
has	O
voluntarily	O
capped	O
its	O
hashing	O
power	O
at	O
39.99	O
%	O
and	O
requested	O
other	O
pools	O
to	O
act	O
responsibly	O
for	O
the	O
benefit	O
of	O
the	O
whole	O
network	B-General_Concept
.	O
</s>
<s>
Bitcoin	B-General_Concept
is	O
pseudonymous	O
,	O
meaning	O
that	O
funds	O
are	O
not	O
tied	O
to	O
real-world	O
entities	O
but	O
rather	O
bitcoin	B-General_Concept
addresses	O
.	O
</s>
<s>
Owners	O
of	O
bitcoin	B-General_Concept
addresses	O
are	O
not	O
explicitly	O
identified	O
,	O
but	O
all	O
transactions	O
on	O
the	O
blockchain	B-Application
are	O
public	O
.	O
</s>
<s>
Additionally	O
,	O
bitcoin	B-General_Concept
exchanges	O
,	O
where	O
bitcoins	B-General_Concept
are	O
traded	O
for	O
traditional	O
currencies	O
,	O
may	O
be	O
required	O
by	O
law	O
to	O
collect	O
personal	O
information	O
.	O
</s>
<s>
To	O
heighten	O
financial	O
privacy	O
,	O
a	O
new	O
bitcoin	B-General_Concept
address	O
can	O
be	O
generated	O
for	O
each	O
transaction	O
.	O
</s>
<s>
While	O
the	O
Bitcoin	B-General_Concept
network	I-General_Concept
treats	O
each	O
bitcoin	B-General_Concept
the	O
same	O
,	O
thus	O
establishing	O
the	O
basic	O
level	O
of	O
fungibility	O
,	O
applications	O
and	O
individuals	O
who	O
use	O
the	O
network	B-General_Concept
are	O
free	O
to	O
break	O
that	O
principle	O
.	O
</s>
<s>
For	O
instance	O
,	O
wallets	O
and	O
similar	O
software	O
technically	O
handle	O
all	O
bitcoins	B-General_Concept
equally	O
,	O
none	O
is	O
different	O
from	O
another	O
.	O
</s>
<s>
Still	O
,	O
the	O
history	O
of	O
each	O
bitcoin	B-General_Concept
is	O
registered	O
and	O
publicly	O
available	O
in	O
the	O
blockchain	B-Application
ledger	B-Language
,	O
and	O
that	O
can	O
allow	O
users	O
of	O
chain	O
analysis	O
to	O
refuse	O
to	O
accept	O
bitcoins	B-General_Concept
coming	O
from	O
controversial	O
transactions	O
.	O
</s>
<s>
Gox	O
froze	O
accounts	O
of	O
users	O
who	O
deposited	O
bitcoins	B-General_Concept
that	O
were	O
known	O
to	O
have	O
just	O
been	O
stolen	O
.	O
</s>
<s>
A	O
wallet	O
stores	O
the	O
information	O
necessary	O
to	O
transact	O
bitcoins	B-General_Concept
.	O
</s>
<s>
While	O
wallets	O
are	O
often	O
described	O
as	O
a	O
place	O
to	O
hold	O
or	O
store	O
bitcoins	B-General_Concept
,	O
due	O
to	O
the	O
nature	O
of	O
the	O
system	O
,	O
bitcoins	B-General_Concept
are	O
inseparable	O
from	O
the	O
blockchain	B-Application
transaction	O
ledger	B-Language
.	O
</s>
<s>
A	O
wallet	O
is	O
more	O
correctly	O
defined	O
as	O
something	O
that	O
"	O
stores	O
the	O
digital	O
credentials	O
for	O
your	O
bitcoin	B-General_Concept
holdings	O
"	O
and	O
allows	O
one	O
to	O
access	O
(	O
and	O
spend	O
)	O
them	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
uses	O
public-key	B-Application
cryptography	I-Application
,	O
in	O
which	O
two	O
cryptographic	O
keys	O
,	O
one	O
public	O
and	O
one	O
private	O
,	O
are	O
generated	O
.	O
</s>
<s>
The	O
first	O
wallet	O
program	O
,	O
simply	O
named	O
Bitcoin	B-General_Concept
,	O
and	O
sometimes	O
referred	O
to	O
as	O
the	O
Satoshi	O
client	O
,	O
was	O
released	O
in	O
2009	O
by	O
Satoshi	O
Nakamoto	O
as	O
open-source	B-Application
software	I-Application
.	O
</s>
<s>
In	O
version	O
0.5	O
the	O
client	O
moved	O
from	O
the	O
wxWidgets	B-Language
user	O
interface	O
toolkit	O
to	O
Qt	B-Language
,	O
and	O
the	O
whole	O
bundle	O
was	O
referred	O
to	O
as	O
Bitcoin-Qt	B-Protocol
.	O
</s>
<s>
After	O
the	O
release	O
of	O
version	O
0.9	O
,	O
the	O
software	O
bundle	O
was	O
renamed	O
Bitcoin	B-General_Concept
Core	O
to	O
distinguish	O
itself	O
from	O
the	O
underlying	O
network	B-General_Concept
.	O
</s>
<s>
Bitcoin	B-General_Concept
Core	O
is	O
,	O
perhaps	O
,	O
the	O
best	O
known	O
implementation	O
or	O
client	O
.	O
</s>
<s>
Forks	B-Protocol
of	I-Protocol
Bitcoin	I-Protocol
Core	O
exist	O
,	O
such	O
as	O
Bitcoin	B-Protocol
XT	I-Protocol
,	O
Bitcoin	B-Application
Unlimited	I-Application
,	O
and	O
Parity	O
Bitcoin	B-General_Concept
.	O
</s>
<s>
Full	O
clients	O
verify	O
transactions	O
directly	O
by	O
downloading	O
a	O
full	O
copy	O
of	O
the	O
blockchain	B-Application
(	O
over	O
150GB	O
)	O
.	O
</s>
<s>
Full	O
clients	O
check	O
the	O
validity	O
of	O
mined	O
blocks	O
,	O
preventing	O
them	O
from	O
transacting	O
on	O
a	O
chain	O
that	O
breaks	O
or	O
alters	O
network	B-General_Concept
rules	O
.	O
</s>
<s>
Because	O
of	O
its	O
size	O
and	O
complexity	O
,	O
downloading	O
and	O
verifying	O
the	O
entire	O
blockchain	B-Application
is	O
not	O
suitable	O
for	O
all	O
computing	O
devices	O
.	O
</s>
<s>
Lightweight	O
clients	O
consult	O
full	O
nodes	B-Protocol
to	O
send	O
and	O
receive	O
transactions	O
without	O
requiring	O
a	O
local	O
copy	O
of	O
the	O
entire	O
blockchain	B-Application
(	O
see	O
simplified	O
payment	O
verification	O
–	O
SPV	O
)	O
.	O
</s>
<s>
When	O
using	O
a	O
lightweight	O
wallet	O
,	O
however	O
,	O
the	O
user	O
must	O
trust	O
full	O
nodes	B-Protocol
,	O
as	O
it	O
can	O
report	O
faulty	O
values	O
back	O
to	O
the	O
user	O
.	O
</s>
<s>
Lightweight	O
clients	O
follow	O
the	O
longest	O
blockchain	B-Application
and	O
do	O
not	O
ensure	O
it	O
is	O
valid	O
,	O
requiring	O
trust	O
in	O
full	O
nodes	B-Protocol
.	O
</s>
<s>
A	O
malicious	O
provider	O
or	O
a	O
breach	O
in	O
server	O
security	O
may	O
cause	O
entrusted	O
bitcoins	B-General_Concept
to	O
be	O
stolen	O
.	O
</s>
<s>
Wallet	O
software	O
is	O
targeted	O
by	O
hackers	O
because	O
of	O
the	O
lucrative	O
potential	O
for	O
stealing	B-Architecture
bitcoins	I-Architecture
.	O
</s>
<s>
A	O
technique	O
called	O
"	O
cold	O
storage	O
"	O
keeps	O
private	B-Application
keys	I-Application
out	O
of	O
reach	O
of	O
hackers	O
;	O
this	O
is	O
accomplished	O
by	O
keeping	O
private	B-Application
keys	I-Application
offline	O
at	O
all	O
times	O
by	O
generating	O
them	O
on	O
a	O
device	O
that	O
is	O
not	B-Architecture
connected	I-Architecture
to	I-Architecture
the	I-Architecture
internet	I-Architecture
.	O
</s>
<s>
The	O
credentials	O
necessary	O
to	O
spend	O
bitcoins	B-General_Concept
can	O
be	O
stored	O
offline	O
in	O
a	O
number	O
of	O
different	O
ways	O
,	O
from	O
specialized	O
hardware	B-Protocol
wallets	I-Protocol
to	O
simple	O
paper	O
printouts	O
of	O
the	O
private	B-Application
key	I-Application
.	O
</s>
<s>
A	O
hardware	B-Protocol
wallet	I-Protocol
is	O
a	O
computer	O
peripheral	O
that	O
signs	O
transactions	O
as	O
requested	O
by	O
the	O
user	O
.	O
</s>
<s>
These	O
devices	O
store	O
private	B-Application
keys	I-Application
and	O
carry	O
out	O
signing	O
and	O
encryption	O
internally	O
,	O
and	O
do	O
not	O
share	O
any	O
sensitive	O
information	O
with	O
the	O
host	O
computer	O
except	O
already	O
signed	O
(	O
and	O
thus	O
unalterable	O
)	O
transactions	O
.	O
</s>
<s>
Because	O
hardware	B-Protocol
wallets	I-Protocol
never	O
expose	O
their	O
private	B-Application
keys	I-Application
,	O
even	O
computers	O
that	O
may	O
be	O
compromised	O
by	O
malware	O
do	O
not	O
have	O
a	O
vector	O
to	O
access	O
or	O
steal	O
them	O
.	O
</s>
<s>
The	O
user	O
sets	O
a	O
passcode	O
when	O
setting	O
up	O
a	O
hardware	B-Protocol
wallet	I-Protocol
.	O
</s>
<s>
As	O
hardware	B-Protocol
wallets	I-Protocol
are	O
tamper-resistant	O
,	O
the	O
passcode	O
will	O
be	O
needed	O
to	O
extract	O
any	O
money	O
.	O
</s>
<s>
A	O
paper	O
wallet	O
is	O
created	O
with	O
a	O
keypair	B-Application
generated	O
on	O
a	O
computer	B-Architecture
with	I-Architecture
no	I-Architecture
internet	I-Architecture
connection	I-Architecture
;	O
the	O
private	B-Application
key	I-Application
is	O
written	O
or	O
printed	O
onto	O
the	O
paper	O
and	O
then	O
erased	O
from	O
the	O
computer	O
.	O
</s>
<s>
Physical	O
wallets	O
can	O
also	O
take	O
the	O
form	O
of	O
metal	O
token	O
coins	O
with	O
a	O
private	B-Application
key	I-Application
accessible	O
under	O
a	O
security	O
hologram	O
in	O
a	O
recess	O
struck	O
on	O
the	O
reverse	O
side	O
.	O
</s>
<s>
The	O
security	O
hologram	O
self-destructs	O
when	O
removed	O
from	O
the	O
token	O
,	O
showing	O
that	O
the	O
private	B-Application
key	I-Application
has	O
been	O
accessed	O
.	O
</s>
<s>
Originally	O
,	O
these	O
tokens	O
were	O
struck	O
in	O
brass	O
and	O
other	O
base	O
metals	O
,	O
but	O
later	O
used	O
precious	O
metals	O
as	O
bitcoin	B-General_Concept
grew	O
in	O
value	O
and	O
popularity	O
.	O
</s>
<s>
The	O
British	O
Museum	O
's	O
coin	O
collection	O
includes	O
four	O
specimens	O
from	O
the	O
earliest	O
series	O
of	O
funded	O
bitcoin	B-General_Concept
tokens	O
;	O
one	O
is	O
currently	O
on	O
display	O
in	O
the	O
museum	O
's	O
money	O
gallery	O
.	O
</s>
<s>
In	O
2013	O
,	O
a	O
Utah	O
manufacturer	O
of	O
these	O
tokens	O
was	O
ordered	O
by	O
the	O
Financial	O
Crimes	O
Enforcement	O
Network	B-General_Concept
(	O
FinCEN	O
)	O
to	O
register	O
as	O
a	O
money	O
services	O
business	O
before	O
producing	O
any	O
more	O
funded	O
bitcoin	B-General_Concept
tokens	O
.	O
</s>
<s>
The	O
domain	O
name	O
bitcoin.org	O
was	O
registered	O
on	O
18	O
August	O
2008	O
.	O
</s>
<s>
On	O
31	O
October	O
2008	O
,	O
a	O
link	O
to	O
a	O
paper	O
authored	O
by	O
Satoshi	O
Nakamoto	O
titled	O
Bitcoin	B-General_Concept
:	O
A	O
Peer-to-Peer	O
Electronic	O
Cash	O
System	O
was	O
posted	O
to	O
a	O
cryptography	O
mailing	O
list	O
.	O
</s>
<s>
Nakamoto	O
implemented	O
the	O
bitcoin	B-General_Concept
software	O
as	O
open-source	B-Application
code	I-Application
and	O
released	O
it	O
in	O
January	O
2009	O
.	O
</s>
<s>
No	O
uniform	O
convention	O
for	O
bitcoin	B-General_Concept
capitalization	O
exists	O
;	O
some	O
sources	O
use	O
Bitcoin	B-General_Concept
,	O
capitalized	O
,	O
to	O
refer	O
to	O
the	O
technology	O
and	O
network	B-General_Concept
and	O
bitcoin	B-General_Concept
,	O
lowercase	O
,	O
for	O
the	O
unit	O
of	O
account	O
.	O
</s>
<s>
The	O
Wall	O
Street	O
Journal	O
,	O
The	O
Chronicle	O
of	O
Higher	O
Education	O
,	O
and	O
the	B-Application
Oxford	I-Application
English	I-Application
Dictionary	I-Application
advocate	O
the	O
use	O
of	O
lowercase	O
bitcoin	B-General_Concept
in	O
all	O
cases	O
.	O
</s>
<s>
On	O
3	O
January	O
2009	O
,	O
the	O
bitcoin	B-General_Concept
network	I-General_Concept
was	O
created	O
when	O
Nakamoto	O
mined	O
the	O
starting	O
block	O
of	O
the	O
chain	O
,	O
known	O
as	O
the	O
genesis	O
block	O
.	O
</s>
<s>
The	O
receiver	O
of	O
the	O
first	O
bitcoin	B-General_Concept
transaction	O
was	O
Hal	O
Finney	O
,	O
who	O
had	O
created	O
the	O
first	O
reusable	O
Proof-of-work	O
system	O
system	O
(	O
RPoW	O
)	O
in	O
2004	O
.	O
</s>
<s>
Finney	O
downloaded	O
the	O
bitcoin	B-General_Concept
software	O
on	O
its	O
release	O
date	O
,	O
and	O
on	O
12	O
January	O
2009	O
received	O
ten	O
bitcoins	B-General_Concept
from	O
Nakamoto	O
.	O
</s>
<s>
Other	O
early	O
cypherpunk	O
supporters	O
were	O
creators	O
of	O
bitcoin	B-General_Concept
predecessors	O
:	O
Wei	O
Dai	O
,	O
creator	O
of	O
b-money	O
,	O
and	O
Nick	O
Szabo	O
,	O
creator	O
of	O
bit	O
gold	O
.	O
</s>
<s>
In	O
2010	O
,	O
the	O
first	O
known	O
commercial	O
transaction	O
using	O
bitcoin	B-General_Concept
occurred	O
when	O
programmer	O
Laszlo	O
Hanyecz	O
bought	O
two	O
Papa	O
John	O
's	O
pizzas	O
for	O
₿	O
10,000	O
from	O
Jeremy	O
Sturdivant	O
.	O
</s>
<s>
Blockchain	B-Application
analysts	O
estimate	O
that	O
Nakamoto	O
had	O
mined	O
about	O
one	O
million	O
bitcoins	B-General_Concept
before	O
disappearing	O
in	O
2010	O
when	O
he	O
handed	O
the	O
network	B-General_Concept
alert	O
key	O
and	O
control	O
of	O
the	O
code	O
repository	O
over	O
to	O
Gavin	O
Andresen	O
.	O
</s>
<s>
Andresen	O
later	O
became	O
lead	O
developer	O
at	O
the	O
Bitcoin	B-General_Concept
Foundation	O
.	O
</s>
<s>
This	O
left	O
opportunity	O
for	O
controversy	O
to	O
develop	O
over	O
the	O
future	O
development	O
path	O
of	O
bitcoin	B-General_Concept
,	O
in	O
contrast	O
to	O
the	O
perceived	O
authority	O
of	O
Nakamoto	O
's	O
contributions	O
.	O
</s>
<s>
After	O
early	O
"	O
proof-of-concept	O
"	O
transactions	O
,	O
the	O
first	O
major	O
users	O
of	O
bitcoin	B-General_Concept
were	O
black	O
markets	O
,	O
such	O
as	O
Silk	O
Road	O
.	O
</s>
<s>
During	O
its	O
30	O
months	O
of	O
existence	O
,	O
beginning	O
in	O
February	O
2011	O
,	O
Silk	O
Road	O
exclusively	O
accepted	O
bitcoins	B-General_Concept
as	O
payment	O
,	O
transacting	O
₿	O
9.9million	O
,	O
worth	O
about	O
$214million	O
.	O
</s>
<s>
In	O
2011	O
,	O
the	O
price	O
started	O
at	O
$0.30	O
per	O
bitcoin	B-General_Concept
,	O
growing	O
to	O
$5.27	O
for	O
the	O
year	O
.	O
</s>
<s>
In	O
2012	O
,	O
bitcoin	B-General_Concept
prices	O
started	O
at	O
$5.27	O
,	O
growing	O
to	O
$13.30	O
for	O
the	O
year	O
.	O
</s>
<s>
The	O
Bitcoin	B-General_Concept
Foundation	O
was	O
founded	O
in	O
September	O
2012	O
to	O
promote	O
bitcoin	B-General_Concept
's	O
development	O
and	O
uptake	O
.	O
</s>
<s>
On	O
1	O
November	O
2011	O
,	O
the	O
reference	O
implementation	O
Bitcoin-Qt	B-Protocol
version	O
0.5.0	O
was	O
released	O
.	O
</s>
<s>
It	O
introduced	O
a	O
front	B-Architecture
end	I-Architecture
that	O
used	O
the	O
Qt	B-Language
user	I-Language
interface	I-Language
toolkit	I-Language
.	O
</s>
<s>
The	O
software	O
previously	O
used	O
Berkeley	B-Language
DB	I-Language
for	O
database	O
management	O
.	O
</s>
<s>
Developers	O
switched	O
to	O
LevelDB	B-Language
in	O
release	O
0.8	O
in	O
order	O
to	O
reduce	O
blockchain	B-Application
synchronization	O
time	O
.	O
</s>
<s>
The	O
update	O
to	O
this	O
release	O
resulted	O
in	O
a	O
minor	O
blockchain	B-Application
fork	B-Application
on	O
11	O
March	O
2013	O
.	O
</s>
<s>
The	O
fork	B-Application
was	O
resolved	O
shortly	O
afterwards	O
.	O
</s>
<s>
Seeding	O
nodes	B-Protocol
through	O
IRC	B-Protocol
was	O
discontinued	O
in	O
version	O
0.8.2	O
.	O
</s>
<s>
From	O
version	O
0.9.0	O
the	O
software	O
was	O
renamed	O
to	O
Bitcoin	B-General_Concept
Core	O
.	O
</s>
<s>
Although	O
Bitcoin	B-General_Concept
Core	O
does	O
not	O
use	O
OpenSSL	B-Language
for	O
the	O
operation	O
of	O
the	O
network	B-General_Concept
,	O
the	O
software	O
did	O
use	O
OpenSSL	B-Language
for	O
remote	B-Operating_System
procedure	I-Operating_System
calls	I-Operating_System
.	O
</s>
<s>
Version	O
0.9.1	O
was	O
released	O
to	O
remove	O
the	O
network	B-General_Concept
's	O
vulnerability	O
to	O
the	O
Heartbleed	B-Error_Name
bug	I-Error_Name
.	O
</s>
<s>
In	O
March	O
2013	O
the	O
blockchain	B-Application
temporarily	O
split	O
into	O
two	O
independent	O
chains	O
with	O
different	O
rules	O
due	O
to	O
a	O
bug	O
in	O
version	O
0.8	O
of	O
the	O
bitcoin	B-General_Concept
software	O
.	O
</s>
<s>
The	O
two	O
blockchains	B-Application
operated	O
simultaneously	O
for	O
six	O
hours	O
,	O
each	O
with	O
its	O
own	O
version	O
of	O
the	O
transaction	O
history	O
from	O
the	O
moment	O
of	O
the	O
split	O
.	O
</s>
<s>
Normal	O
operation	O
was	O
restored	O
when	O
the	O
majority	O
of	O
the	O
network	B-General_Concept
downgraded	O
to	O
version	O
0.7	O
of	O
the	O
bitcoin	B-General_Concept
software	O
,	O
selecting	O
the	O
backwards-compatible	O
version	O
of	O
the	O
blockchain	B-Application
.	O
</s>
<s>
As	O
a	O
result	O
,	O
this	O
blockchain	B-Application
became	O
the	O
longest	O
chain	O
and	O
could	O
be	O
accepted	O
by	O
all	O
participants	O
,	O
regardless	O
of	O
their	O
bitcoin	B-General_Concept
software	O
version	O
.	O
</s>
<s>
Gox	O
exchange	O
briefly	O
halted	O
bitcoin	B-General_Concept
deposits	O
and	O
the	O
price	O
dropped	O
by	O
23%	O
to	O
$37	O
before	O
recovering	O
to	O
the	O
previous	O
level	O
of	O
approximately	O
$48	O
in	O
the	O
following	O
hours	O
.	O
</s>
<s>
The	O
US	O
Financial	O
Crimes	O
Enforcement	O
Network	B-General_Concept
(	O
FinCEN	O
)	O
established	O
regulatory	O
guidelines	O
for	O
"	O
decentralized	O
virtual	O
currencies	O
"	O
such	O
as	O
bitcoin	B-General_Concept
,	O
classifying	O
American	O
bitcoin	B-General_Concept
miners	O
who	O
sell	O
their	O
generated	O
bitcoins	B-General_Concept
as	O
Money	O
Service	O
Businesses	O
(	O
MSBs	O
)	O
,	O
that	O
are	O
subject	O
to	O
registration	O
or	O
other	O
legal	O
obligations	O
.	O
</s>
<s>
Gox	O
experienced	O
processing	O
delays	O
due	O
to	O
insufficient	O
capacity	O
resulting	O
in	O
the	O
bitcoin	B-General_Concept
price	O
dropping	O
from	O
$266	O
to	O
$76	O
before	O
returning	O
to	O
$160	O
within	O
six	O
hours	O
.	O
</s>
<s>
The	O
bitcoin	B-General_Concept
price	O
rose	O
to	O
$259	O
on	O
10	O
April	O
,	O
but	O
then	O
crashed	O
by	O
83%	O
to	O
$45	O
over	O
the	O
next	O
three	O
days	O
.	O
</s>
<s>
This	O
marked	O
the	O
first	O
time	O
a	O
government	O
agency	O
had	O
seized	O
bitcoin	B-General_Concept
.	O
</s>
<s>
These	O
bitcoins	B-General_Concept
were	O
sold	O
at	O
blind	O
auction	O
by	O
the	O
United	O
States	O
Marshals	O
Service	O
to	O
venture	O
capital	O
investor	O
Tim	O
Draper	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
's	O
price	O
rose	O
to	O
$755	O
on	O
19	O
November	O
and	O
crashed	O
by	O
50%	O
to	O
$378	O
the	O
same	O
day	O
.	O
</s>
<s>
On	O
5	O
December	O
2013	O
,	O
the	O
People	O
's	O
Bank	O
of	O
China	O
prohibited	O
Chinese	O
financial	O
institutions	O
from	O
using	O
bitcoin	B-General_Concept
.	O
</s>
<s>
After	O
the	O
announcement	O
,	O
the	O
value	O
of	O
bitcoin	B-General_Concept
dropped	O
,	O
and	O
Baidu	B-Application
no	O
longer	O
accepted	O
bitcoins	B-General_Concept
for	O
certain	O
services	O
.	O
</s>
<s>
On	O
30	O
July	O
2014	O
,	O
the	O
Wikimedia	O
Foundation	O
started	O
accepting	O
donations	O
of	O
bitcoin	B-General_Concept
.	O
</s>
<s>
It	O
introduced	O
a	O
consensus	O
library	O
which	O
gave	O
programmers	O
easy	O
access	O
to	O
the	O
rules	O
governing	O
consensus	O
on	O
the	O
network	B-General_Concept
.	O
</s>
<s>
In	O
July	O
2016	O
,	O
the	O
CheckSequenceVerify	O
soft	O
fork	B-Application
activated	O
.	O
</s>
<s>
In	O
August	O
2016	O
,	O
the	O
Bitfinex	B-Protocol
cryptocurrency	O
exchange	O
platform	O
was	O
hacked	O
in	O
the	O
second-largest	O
breach	O
of	O
a	O
Bitcoin	B-General_Concept
exchange	O
platform	O
up	O
to	O
that	O
time	O
,	O
and	O
₿119	O
,	O
756	O
,	O
worth	O
about	O
$72million	O
at	O
the	O
time	O
,	O
were	O
stolen	O
.	O
</s>
<s>
In	O
October	O
2016	O
,	O
Bitcoin	B-General_Concept
Core	O
's	O
0.13.1	O
release	O
featured	O
the	O
"	O
Segwit	O
"	O
soft	O
fork	B-Application
that	O
included	O
a	O
scaling	O
improvement	O
aiming	O
to	O
optimize	O
the	O
bitcoin	B-General_Concept
blocksize	O
.	O
</s>
<s>
This	O
release	O
featured	O
Segregated	O
Witness	O
(	O
SegWit	O
)	O
which	O
aimed	O
to	O
place	O
downward	O
pressure	O
on	O
transaction	O
fees	O
as	O
well	O
as	O
increase	O
the	O
maximum	O
transaction	O
capacity	O
of	O
the	O
network	B-General_Concept
.	O
</s>
<s>
Research	O
produced	O
by	O
the	O
University	O
of	O
Cambridge	O
estimated	O
that	O
in	O
2017	O
,	O
there	O
were	O
2.9	O
to	O
5.8	O
million	O
unique	O
users	O
using	O
a	O
cryptocurrency	B-Protocol
wallet	I-Protocol
,	O
most	O
of	O
them	O
using	O
bitcoin	B-General_Concept
.	O
</s>
<s>
Segwit	O
was	O
intended	O
to	O
support	O
the	O
Lightning	B-Protocol
Network	I-Protocol
as	O
well	O
as	O
improve	O
scalability	O
.	O
</s>
<s>
SegWit	O
was	O
subsequently	O
activated	O
on	O
the	O
network	B-General_Concept
on	O
24	O
August	O
2017	O
.	O
</s>
<s>
The	O
bitcoin	B-General_Concept
price	O
rose	O
almost	O
50%	O
in	O
the	O
week	O
following	O
SegWit	O
's	O
approval	O
.	O
</s>
<s>
On	O
21	O
July	O
2017	O
,	O
bitcoin	B-General_Concept
was	O
trading	O
at	O
$2	O
,	O
748	O
,	O
up	O
52%	O
from	O
14	O
July	O
2017	O
's	O
$	O
1,835	O
.	O
</s>
<s>
Supporters	O
of	O
large	O
blocks	O
who	O
were	O
dissatisfied	O
with	O
the	O
activation	O
of	O
SegWit	O
forked	O
the	O
software	O
on	O
1	O
August	O
2017	O
to	O
create	O
Bitcoin	B-Protocol
Cash	I-Protocol
,	O
becoming	O
one	O
of	O
many	O
forks	B-Protocol
of	I-Protocol
bitcoin	I-Protocol
such	O
as	O
Bitcoin	B-Protocol
Gold	I-Protocol
.	O
</s>
<s>
China	O
banned	O
trading	O
in	O
bitcoin	B-General_Concept
,	O
with	O
first	O
steps	O
taken	O
in	O
September	O
2017	O
,	O
and	O
a	O
complete	O
ban	O
that	O
started	O
on	O
1	O
February	O
2018	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
prices	O
then	O
fell	O
from	O
$	O
9,052	O
to	O
$	O
6,914	O
on	O
5	O
February	O
2018	O
.	O
</s>
<s>
The	O
percentage	O
of	O
bitcoin	B-General_Concept
trading	O
in	O
the	O
Chinese	O
renminbi	O
fell	O
from	O
over	O
90%	O
in	O
September	O
2017	O
to	O
less	O
than	O
1%	O
in	O
June	O
2018	O
.	O
</s>
<s>
Throughout	O
the	O
rest	O
of	O
the	O
first	O
half	O
of	O
2018	O
,	O
bitcoin	B-General_Concept
's	O
price	O
fluctuated	O
between	O
$	O
11,480	O
and	O
$	O
5,848	O
.	O
</s>
<s>
On	O
1	O
July	O
2018	O
,	O
bitcoin	B-General_Concept
's	O
price	O
was	O
$	O
6,343	O
.	O
</s>
<s>
In	O
September	O
2018	O
,	O
an	O
anonymous	O
party	O
discovered	O
and	O
reported	O
an	O
invalid-block	O
denial-of-server	O
vulnerability	O
to	O
developers	O
of	O
Bitcoin	B-General_Concept
Core	O
,	O
Bitcoin	B-General_Concept
ABC	O
and	O
Bitcoin	B-Application
Unlimited	I-Application
.	O
</s>
<s>
Further	O
analysis	O
by	O
bitcoin	B-General_Concept
developers	O
showed	O
the	O
issue	O
could	O
also	O
allow	O
the	O
creation	O
of	O
blocks	O
violating	O
the	O
21	O
million	O
coin	O
limit	O
and	O
was	O
assigned	O
and	O
the	O
issue	O
resolved	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
prices	O
were	O
negatively	O
affected	O
by	O
several	O
hacks	O
or	O
thefts	O
from	O
cryptocurrency	O
exchanges	O
,	O
including	O
thefts	O
from	O
Coincheck	B-Protocol
in	O
January	O
2018	O
,	O
Bithumb	B-Protocol
in	O
June	O
,	O
and	O
Bancor	O
in	O
July	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
's	O
price	O
was	O
affected	O
even	O
though	O
other	O
cryptocurrencies	O
were	O
stolen	O
at	O
Coinrail	O
and	O
Bancor	O
as	O
investors	O
worried	O
about	O
the	O
security	O
of	O
cryptocurrency	O
exchanges	O
.	O
</s>
<s>
In	O
September	O
2019	O
,	O
the	O
Intercontinental	O
Exchange	O
(	O
the	O
owner	O
of	O
the	O
NYSE	O
)	O
began	O
trading	O
of	O
bitcoin	B-General_Concept
futures	O
on	O
its	O
exchange	O
called	O
Bakkt	O
.	O
</s>
<s>
Bakkt	O
also	O
announced	O
that	O
it	O
would	O
launch	O
options	O
on	O
bitcoin	B-General_Concept
in	O
December	O
2019	O
.	O
</s>
<s>
In	O
December	O
2019	O
,	O
YouTube	B-General_Concept
removed	O
bitcoin	B-General_Concept
and	O
cryptocurrency	O
videos	O
,	O
but	O
later	O
restored	O
the	O
content	O
after	O
judging	O
they	O
had	O
"	O
made	O
the	O
wrong	O
call	O
"	O
.	O
</s>
<s>
In	O
February	O
2019	O
,	O
Canadian	O
cryptocurrency	O
exchange	O
Quadriga	B-Protocol
Fintech	I-Protocol
Solutions	I-Protocol
failed	O
with	O
approximately	O
$200	O
million	O
missing	O
.	O
</s>
<s>
On	O
13	O
March	O
2020	O
,	O
bitcoin	B-General_Concept
fell	O
below	O
$	O
4,000	O
during	O
a	O
broad	O
market	O
selloff	O
,	O
after	O
trading	O
above	O
$	O
10,000	O
in	O
February	O
2020	O
.	O
</s>
<s>
On	O
11	O
March	O
2020	O
,	O
281,000	O
bitcoins	B-General_Concept
were	O
sold	O
,	O
held	O
by	O
owners	O
for	O
only	O
thirty	O
days	O
.	O
</s>
<s>
This	O
compared	O
to	O
₿	O
4,131	O
that	O
had	O
laid	O
dormant	O
for	O
a	O
year	O
or	O
more	O
,	O
indicating	O
that	O
the	O
vast	O
majority	O
of	O
the	O
bitcoin	B-General_Concept
volatility	O
on	O
that	O
day	O
was	O
from	O
recent	O
buyers	O
.	O
</s>
<s>
During	O
the	O
week	O
of	O
11	O
March	O
2020	O
,	O
cryptocurrency	O
exchange	O
Kraken	O
experienced	O
an	O
83%	O
increase	O
in	O
the	O
number	O
of	O
account	O
signups	O
over	O
the	O
week	O
of	O
bitcoin	B-General_Concept
's	O
price	O
collapse	O
,	O
a	O
result	O
of	O
buyers	O
looking	O
to	O
capitalize	O
on	O
the	O
low	O
price	O
.	O
</s>
<s>
In	O
August	O
2020	O
,	O
MicroStrategy	O
invested	O
$250	O
million	O
in	O
bitcoin	B-General_Concept
as	O
a	O
treasury	O
reserve	O
asset	O
.	O
</s>
<s>
In	O
October	O
2020	O
,	O
Square	O
,	O
Inc	O
.	O
placed	O
approximately	O
1%	O
of	O
total	O
assets	O
( $50	O
million	O
)	O
in	O
bitcoin	B-General_Concept
.	O
</s>
<s>
In	O
November	O
2020	O
,	O
PayPal	O
announced	O
that	O
US	O
users	O
could	O
buy	O
,	O
hold	O
,	O
or	O
sell	O
bitcoin	B-General_Concept
.	O
</s>
<s>
On	O
30	O
November	O
2020	O
,	O
the	O
bitcoin	B-General_Concept
value	O
reached	O
a	O
new	O
all-time	O
high	O
of	O
$19	O
,	O
860	O
,	O
topping	O
the	O
previous	O
high	O
of	O
December	O
2017	O
.	O
</s>
<s>
In	O
December	O
2020	O
,	O
Massachusetts	O
Mutual	O
Life	O
Insurance	O
Company	O
announced	O
a	O
bitcoin	B-General_Concept
purchase	O
of	O
US$100	O
million	O
,	O
or	O
roughly	O
0.04	O
%	O
of	O
its	O
general	O
investment	O
account	O
.	O
</s>
<s>
On	O
19	O
January	O
2021	O
,	O
Elon	O
Musk	O
placed	O
the	O
handle	O
#Bitcoin	O
in	O
his	O
Twitter	B-Application
profile	O
,	O
tweeting	O
"	O
In	O
retrospect	O
,	O
it	O
was	O
inevitable	O
"	O
,	O
which	O
caused	O
the	O
price	O
to	O
briefly	O
rise	O
about	O
$	O
5,000	O
in	O
an	O
hour	O
to	O
$	O
37,299	O
.	O
</s>
<s>
On	O
25	O
January	O
2021	O
,	O
Microstrategy	O
announced	O
that	O
it	O
continued	O
to	O
buy	O
bitcoin	B-General_Concept
and	O
as	O
of	O
the	O
same	O
date	O
it	O
had	O
holdings	O
of	O
₿	O
70,784	O
worth	O
$2.38	O
billion	O
.	O
</s>
<s>
On	O
8	O
February	O
2021	O
Tesla	O
's	O
announcement	O
of	O
a	O
bitcoin	B-General_Concept
purchase	O
of	O
US	O
$1.5	O
billion	O
and	O
the	O
plan	O
to	O
start	O
accepting	O
bitcoin	B-General_Concept
as	O
payment	O
for	O
vehicles	O
,	O
pushed	O
the	O
bitcoin	B-General_Concept
price	O
to	O
$	O
44,141	O
.	O
</s>
<s>
On	O
18	O
February	O
2021	O
,	O
Elon	O
Musk	O
stated	O
that	O
"	O
owning	O
bitcoin	B-General_Concept
was	O
only	O
a	O
little	O
better	O
than	O
holding	O
conventional	O
cash	O
,	O
but	O
that	O
the	O
slight	O
difference	O
made	O
it	O
a	O
better	O
asset	O
to	O
hold	O
"	O
.	O
</s>
<s>
After	O
49	O
days	O
of	O
accepting	O
the	O
digital	O
currency	O
,	O
Tesla	O
reversed	O
course	O
on	O
12	O
May	O
2021	O
,	O
saying	O
they	O
would	O
no	O
longer	O
take	O
bitcoin	B-General_Concept
due	O
to	O
concerns	O
that	O
"	O
mining	O
"	O
the	O
cryptocurrency	O
was	O
contributing	O
to	O
the	O
consumption	O
of	O
fossil	O
fuels	O
and	O
climate	O
change	O
.	O
</s>
<s>
The	O
decision	O
resulted	O
in	O
the	O
price	O
of	O
bitcoin	B-General_Concept
dropping	O
around	O
12%	O
on	O
13	O
May	O
.	O
</s>
<s>
During	O
a	O
July	O
bitcoin	B-General_Concept
conference	O
,	O
Musk	O
suggested	O
Tesla	O
could	O
possibly	O
help	O
bitcoin	B-General_Concept
miners	O
switch	O
to	O
renewable	O
energy	O
in	O
the	O
future	O
and	O
also	O
stated	O
at	O
the	O
same	O
conference	O
that	O
if	O
bitcoin	B-General_Concept
mining	O
reaches	O
,	O
and	O
trends	O
above	O
50	O
percent	O
renewable	O
energy	O
usage	O
,	O
that	O
"	O
Tesla	O
would	O
resume	O
accepting	O
bitcoin.	O
"	O
</s>
<s>
The	O
price	O
for	O
bitcoin	B-General_Concept
rose	O
after	O
this	O
announcement	O
.	O
</s>
<s>
In	O
June	O
2021	O
,	O
the	O
Taproot	O
network	B-Architecture
software	I-Architecture
upgrade	O
was	O
approved	O
,	O
adding	O
support	O
for	O
Schnorr	B-Algorithm
signatures	I-Algorithm
,	O
improved	O
functionality	O
of	O
Smart	B-Application
contracts	I-Application
and	O
Lightning	B-Protocol
Network	I-Protocol
.	O
</s>
<s>
In	O
September	O
2021	O
,	O
Bitcoin	B-General_Concept
in	O
El	O
Salvador	O
became	O
legal	O
tender	O
,	O
alongside	O
the	O
US	O
dollar	O
.	O
</s>
<s>
On	O
16	O
October	O
2021	O
,	O
the	O
SEC	O
approved	O
the	O
ProShares	O
Bitcoin	B-General_Concept
Strategy	O
ETF	O
,	O
a	O
cash-settled	O
futures	O
exchange-traded	O
fund	O
(	O
ETF	O
)	O
.	O
</s>
<s>
The	O
first	O
bitcoin	B-General_Concept
ETF	O
in	O
the	O
United	O
States	O
gained	O
5%	O
on	O
its	O
first	O
trading	O
day	O
on	O
19	O
October	O
2021	O
.	O
</s>
<s>
On	O
25	O
March	O
2022	O
,	O
Pavel	O
Zavalny	O
stated	O
that	O
Russia	O
might	O
accept	O
bitcoin	B-General_Concept
for	O
payment	O
for	O
oil	O
and	O
gas	O
exports	O
,	O
in	O
response	O
to	O
sanctions	O
stemming	O
from	O
the	O
2022	O
Russian	O
invasion	O
of	O
Ukraine	O
.	O
</s>
<s>
On	O
27	O
April	O
2022	O
Central	O
African	O
Republic	O
adopted	O
bitcoin	B-General_Concept
as	O
legal	O
tender	O
alongside	O
the	O
CFA	O
franc	O
.	O
</s>
<s>
On	O
May	O
10	O
,	O
2022	O
,	O
the	O
bitcoin	B-General_Concept
price	O
fell	O
to	O
$31	O
,	O
324	O
,	O
as	O
a	O
result	O
of	O
a	O
collapse	O
of	O
a	O
UST	O
stablecoin	B-Protocol
experiment	O
named	O
Terra	O
,	O
with	O
bitcoin	B-General_Concept
down	O
more	O
than	O
50%	O
since	O
the	O
November	O
2021	O
high	O
.	O
</s>
<s>
By	O
June	O
13	O
,	O
2022	O
,	O
the	O
Celsius	O
Network	B-General_Concept
(	O
a	O
decentralized	B-Protocol
finance	I-Protocol
loan	O
company	O
)	O
halted	O
withdrawals	O
and	O
resulted	O
in	O
the	O
bitcoin	B-General_Concept
price	O
falling	O
below	O
$	O
20,000	O
.	O
</s>
<s>
In	O
May	O
2022	O
,	O
following	O
a	O
vote	O
by	O
Wikipedia	O
editors	O
the	O
previous	O
month	O
,	O
the	O
Wikimedia	O
Foundation	O
announced	O
it	O
would	O
stop	O
accepting	O
donations	O
in	O
bitcoin	B-General_Concept
or	O
other	O
cryptocurrencies	O
—	O
eight	O
years	O
after	O
it	O
had	O
first	O
started	O
taking	O
contributions	O
in	O
bitcoin	B-General_Concept
.	O
</s>
<s>
Satoshi	O
Nakamoto	O
stated	O
in	O
an	O
essay	O
accompanying	O
bitcoin	B-General_Concept
's	O
code	O
that	O
:	O
"	O
The	O
root	O
problem	O
with	O
conventional	O
currencies	O
is	O
all	O
the	O
trust	O
that	O
's	O
required	O
to	O
make	O
it	O
work	O
.	O
</s>
<s>
According	O
to	O
the	O
European	O
Central	O
Bank	O
,	O
the	O
decentralization	O
of	O
money	O
offered	O
by	O
bitcoin	B-General_Concept
has	O
its	O
theoretical	O
roots	O
in	O
the	O
Austrian	O
school	O
of	O
economics	O
,	O
especially	O
with	O
Friedrich	O
von	O
Hayek	O
in	O
his	O
book	O
Denationalisation	O
of	O
Money	O
:	O
The	O
Argument	O
Refined	O
,	O
in	O
which	O
Hayek	O
advocates	O
a	O
complete	O
free	O
market	O
in	O
the	O
production	O
,	O
distribution	O
and	O
management	O
of	O
money	O
to	O
end	O
the	O
monopoly	O
of	O
central	O
banks	O
.	O
</s>
<s>
According	O
to	O
The	O
New	O
York	O
Times	O
,	O
libertarians	O
and	O
anarchists	O
were	O
attracted	O
to	O
the	O
philosophical	O
idea	O
behind	O
bitcoin	B-General_Concept
.	O
</s>
<s>
Early	O
bitcoin	B-General_Concept
supporter	O
Roger	O
Ver	O
said	O
:	O
"	O
At	O
first	O
,	O
almost	O
everyone	O
who	O
got	O
involved	O
did	O
so	O
for	O
philosophical	O
reasons	O
.	O
</s>
<s>
We	O
saw	O
bitcoin	B-General_Concept
as	O
a	O
great	O
idea	O
,	O
as	O
a	O
way	O
to	O
separate	O
money	O
from	O
the	O
state.	O
"	O
</s>
<s>
The	O
Economist	O
describes	O
bitcoin	B-General_Concept
as	O
"	O
a	O
techno-anarchist	O
project	O
to	O
create	O
an	O
online	O
version	O
of	O
cash	O
,	O
a	O
way	O
for	O
people	O
to	O
transact	O
without	O
the	O
possibility	O
of	O
interference	O
from	O
malicious	O
governments	O
or	O
banks	O
"	O
.	O
</s>
<s>
Economist	O
Paul	O
Krugman	O
argues	O
that	O
cryptocurrencies	O
like	O
bitcoin	B-General_Concept
are	O
"	O
something	O
of	O
a	O
cult	O
"	O
based	O
in	O
"	O
paranoid	O
fantasies	O
"	O
of	O
government	O
power	O
.	O
</s>
<s>
Nigel	O
Dodd	O
argues	O
in	O
The	O
Social	O
Life	O
of	O
Bitcoin	B-General_Concept
that	O
the	O
essence	O
of	O
the	O
bitcoin	B-General_Concept
ideology	O
is	O
to	O
remove	O
money	O
from	O
social	O
,	O
as	O
well	O
as	O
governmental	O
,	O
control	O
.	O
</s>
<s>
Dodd	O
quotes	O
a	O
YouTube	B-General_Concept
video	I-General_Concept
,	O
with	O
Roger	O
Ver	O
,	O
Jeff	O
Berwick	O
,	O
Charlie	O
Shrem	O
,	O
Andreas	O
Antonopoulos	O
,	O
Gavin	O
Wood	O
,	O
Trace	O
Meyer	O
and	O
other	O
proponents	O
of	O
bitcoin	B-General_Concept
reading	O
The	O
Declaration	O
of	O
Bitcoin	B-General_Concept
's	O
Independence	O
.	O
</s>
<s>
The	O
declaration	O
includes	O
a	O
message	O
of	O
crypto-anarchism	O
with	O
the	O
words	O
:	O
"	O
Bitcoin	B-General_Concept
is	O
inherently	O
anti-establishment	O
,	O
anti-system	O
,	O
and	O
anti-state	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
undermines	O
governments	O
and	O
disrupts	O
institutions	O
because	O
bitcoin	B-General_Concept
is	O
fundamentally	O
humanitarian.	O
"	O
</s>
<s>
David	O
Golumbia	O
says	O
that	O
the	O
ideas	O
influencing	O
bitcoin	B-General_Concept
advocates	O
emerge	O
from	O
right-wing	O
extremist	O
movements	O
such	O
as	O
the	O
Liberty	O
Lobby	O
and	O
the	O
John	O
Birch	O
Society	O
and	O
their	O
anti-Central	O
Bank	O
rhetoric	O
,	O
or	O
,	O
more	O
recently	O
,	O
Ron	O
Paul	O
and	O
Tea	O
Party-style	O
libertarianism	O
.	O
</s>
<s>
Steve	O
Bannon	O
,	O
who	O
owns	O
a	O
"	O
good	O
stake	O
"	O
in	O
bitcoin	B-General_Concept
,	O
considers	O
it	O
to	O
be	O
"	O
disruptive	O
populism	O
.	O
</s>
<s>
A	O
2014	O
study	O
of	O
Google	B-Application
Trends	I-Application
data	O
found	O
correlations	O
between	O
bitcoin-related	O
searches	O
and	O
ones	O
related	O
to	O
computer	O
programming	O
and	O
illegal	O
activity	O
,	O
but	O
not	O
libertarianism	O
or	O
investment	O
topics	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
is	O
a	O
digital	O
asset	O
designed	O
to	O
work	O
in	O
peer-to-peer	O
transactions	O
as	O
a	O
currency	O
.	O
</s>
<s>
Bitcoins	B-General_Concept
have	O
three	O
qualities	O
useful	O
in	O
a	O
currency	O
,	O
according	O
to	O
The	O
Economist	O
in	O
January	O
2015	O
:	O
they	O
are	O
"	O
hard	O
to	O
earn	O
,	O
limited	O
in	O
supply	O
and	O
easy	O
to	O
verify	O
"	O
.	O
</s>
<s>
Per	O
some	O
researchers	O
,	O
,	O
bitcoin	B-General_Concept
functions	O
more	O
as	O
a	O
payment	O
system	O
than	O
as	O
a	O
currency	O
.	O
</s>
<s>
According	O
to	O
The	O
Economist	O
in	O
2014	O
,	O
bitcoin	B-General_Concept
functions	O
best	O
as	O
a	O
medium	O
of	O
exchange	O
.	O
</s>
<s>
Yale	O
economist	O
Robert	O
J	O
.	O
Shiller	O
writes	O
that	O
bitcoin	B-General_Concept
has	O
potential	O
as	O
a	O
unit	O
of	O
account	O
for	O
measuring	O
the	O
relative	O
value	O
of	O
goods	O
,	O
as	O
with	O
Chile	O
's	O
Unidad	O
de	O
Fomento	O
,	O
but	O
that	O
"	O
Bitcoin	B-General_Concept
in	O
its	O
present	O
form	O
...	O
does	O
n't	O
really	O
solve	O
any	O
sensible	O
economic	O
problem	O
"	O
.	O
</s>
<s>
According	O
to	O
research	O
by	O
the	O
University	O
of	O
Cambridge	O
,	O
between	O
2.9	O
million	O
and	O
5.8	O
million	O
unique	O
users	O
used	O
a	O
cryptocurrency	B-Protocol
wallet	I-Protocol
in	O
2017	O
,	O
most	O
of	O
them	O
for	O
bitcoin	B-General_Concept
.	O
</s>
<s>
Dish	O
Network	B-General_Concept
,	O
a	O
Fortune	O
500	O
subscription	O
TV	O
provider	O
,	O
has	O
been	O
described	O
as	O
the	O
first	O
large	O
company	O
to	O
accept	O
bitcoin	B-General_Concept
,	O
in	O
2014	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
is	O
"	O
not	O
actually	O
usable	O
"	O
for	O
retail	O
transactions	O
because	O
of	O
high	O
costs	O
and	O
the	O
inability	O
to	O
process	O
chargebacks	O
,	O
according	O
to	O
Nicholas	O
Weaver	O
,	O
a	O
researcher	O
quoted	O
by	O
Bloomberg	O
.	O
</s>
<s>
High	O
price	O
volatility	O
and	O
transaction	O
fees	O
make	O
paying	O
for	O
small	O
retail	O
purchases	O
with	O
bitcoin	B-General_Concept
impractical	O
,	O
according	O
to	O
economist	O
Kim	O
Grauer	O
.	O
</s>
<s>
However	O
,	O
bitcoin	B-General_Concept
continues	O
to	O
be	O
used	O
for	O
large-item	O
purchases	O
on	O
sites	O
such	O
as	O
Overstock.com,	O
and	O
for	O
cross-border	O
payments	O
to	O
freelancers	B-Language
and	O
other	O
vendors	O
.	O
</s>
<s>
In	O
2017	O
and	O
2018	O
,	O
bitcoin	B-General_Concept
's	O
acceptance	O
among	O
major	O
online	O
retailers	O
included	O
only	O
three	O
of	O
the	O
top	O
500	O
U.S.	O
online	O
merchants	O
,	O
down	O
from	O
five	O
in	O
2016	O
.	O
</s>
<s>
Reasons	O
for	O
this	O
decline	O
include	O
high	O
transaction	O
fees	O
due	O
to	O
bitcoin	B-General_Concept
's	O
scalability	O
issues	O
and	O
long	O
transaction	O
times	O
.	O
</s>
<s>
As	O
of	O
2018	O
,	O
the	O
overwhelming	O
majority	O
of	O
bitcoin	B-General_Concept
transactions	O
took	O
place	O
on	O
cryptocurrency	O
exchanges	O
,	O
rather	O
than	O
being	O
used	O
in	O
transactions	O
with	O
merchants	O
.	O
</s>
<s>
Delays	O
processing	O
payments	O
through	O
the	O
blockchain	B-Application
of	O
about	O
ten	O
minutes	O
make	O
bitcoin	B-General_Concept
use	O
very	O
difficult	O
in	O
a	O
retail	O
setting	O
.	O
</s>
<s>
Prices	O
are	O
not	O
usually	O
quoted	O
in	O
units	O
of	O
bitcoin	B-General_Concept
and	O
many	O
trades	O
involve	O
one	O
,	O
or	O
sometimes	O
two	O
,	O
conversions	O
into	O
conventional	O
currencies	O
.	O
</s>
<s>
Merchants	O
that	O
do	O
accept	O
bitcoin	B-General_Concept
payments	O
may	O
use	O
payment	O
service	O
providers	O
to	O
perform	O
the	O
conversions	O
.	O
</s>
<s>
Bitcoins	B-General_Concept
can	O
be	O
bought	O
on	O
digital	O
currency	O
exchanges	O
.	O
</s>
<s>
Per	O
researchers	O
,	O
"	O
there	O
is	O
little	O
sign	O
of	O
bitcoin	B-General_Concept
use	O
"	O
in	O
international	O
remittances	O
despite	O
high	O
fees	O
charged	O
by	O
banks	O
and	O
Western	O
Union	O
who	O
compete	O
in	O
this	O
market	O
.	O
</s>
<s>
The	O
South	O
China	O
Morning	O
Post	O
,	O
however	O
,	O
mentions	O
the	O
use	O
of	O
bitcoin	B-General_Concept
by	O
Hong	O
Kong	O
workers	O
to	O
transfer	O
money	O
home	O
.	O
</s>
<s>
In	O
2014	O
,	O
the	O
National	O
Australia	O
Bank	O
closed	O
accounts	O
of	O
businesses	O
with	O
ties	O
to	O
bitcoin	B-General_Concept
,	O
and	O
HSBC	O
refused	O
to	O
serve	O
a	O
hedge	O
fund	O
with	O
links	O
to	O
bitcoin	B-General_Concept
.	O
</s>
<s>
On	O
10	O
December	O
2017	O
,	O
the	O
Chicago	O
Board	O
Options	O
Exchange	O
started	O
trading	O
bitcoin	B-General_Concept
futures	O
,	O
followed	O
by	O
the	O
Chicago	O
Mercantile	O
Exchange	O
,	O
which	O
started	O
trading	O
bitcoin	B-General_Concept
futures	O
on	O
17	O
December	O
2017	O
.	O
</s>
<s>
In	O
September	O
2019	O
the	O
Central	O
Bank	O
of	O
Venezuela	O
,	O
at	O
the	O
request	O
of	O
PDVSA	O
,	O
ran	O
tests	O
to	O
determine	O
if	O
bitcoin	B-General_Concept
and	O
ether	B-Application
could	O
be	O
held	O
in	O
central	O
bank	O
's	O
reserves	O
.	O
</s>
<s>
François	O
R	O
.	O
Velde	O
,	O
Senior	O
Economist	O
at	O
the	O
Chicago	O
Fed	O
,	O
described	O
bitcoin	B-General_Concept
as	O
"	O
an	O
elegant	O
solution	O
to	O
the	O
problem	O
of	O
creating	O
a	O
digital	O
currency	O
"	O
.	O
</s>
<s>
David	O
Andolfatto	O
,	O
Vice	O
President	O
at	O
the	O
Federal	O
Reserve	O
Bank	O
of	O
St.	O
Louis	O
,	O
stated	O
that	O
bitcoin	B-General_Concept
is	O
a	O
threat	O
to	O
the	O
establishment	O
,	O
which	O
he	O
argues	O
is	O
a	O
good	O
thing	O
for	O
the	O
Federal	O
Reserve	O
System	O
and	O
other	O
central	O
banks	O
,	O
because	O
it	O
prompts	O
these	O
institutions	O
to	O
operate	O
sound	O
policies	O
.	O
</s>
<s>
The	O
Winklevoss	O
twins	O
have	O
purchased	O
bitcoin	B-General_Concept
.	O
</s>
<s>
In	O
2013	O
,	O
The	O
Washington	O
Post	O
reported	O
a	O
claim	O
that	O
they	O
owned	O
1%	O
of	O
all	O
the	O
bitcoins	B-General_Concept
in	O
existence	O
at	O
the	O
time	O
.	O
</s>
<s>
Other	O
methods	O
of	O
investment	O
are	O
bitcoin	B-General_Concept
funds	O
.	O
</s>
<s>
The	O
first	O
regulated	O
bitcoin	B-General_Concept
fund	O
was	O
established	O
in	O
Jersey	O
in	O
July	O
2014	O
and	O
approved	O
by	O
the	O
Jersey	O
Financial	O
Services	O
Commission	O
.	O
</s>
<s>
Forbes	O
named	O
bitcoin	B-General_Concept
the	O
best	O
investment	O
of	O
2013	O
.	O
</s>
<s>
In	O
2014	O
,	O
Bloomberg	O
named	O
bitcoin	B-General_Concept
one	O
of	O
its	O
worst	O
investments	O
of	O
the	O
year	O
.	O
</s>
<s>
In	O
2015	O
,	O
bitcoin	B-General_Concept
topped	O
Bloomberg	O
's	O
currency	O
tables	O
.	O
</s>
<s>
According	O
to	O
bitinfocharts.com,	O
in	O
2017	O
,	O
there	O
were	O
9,272	O
bitcoin	B-General_Concept
wallets	O
with	O
more	O
than	O
$1	O
million	O
worth	O
of	O
bitcoins	B-General_Concept
.	O
</s>
<s>
The	O
exact	O
number	O
of	O
bitcoin	B-General_Concept
millionaires	O
is	O
uncertain	O
as	O
a	O
single	O
person	O
can	O
have	O
more	O
than	O
one	O
bitcoin	B-General_Concept
wallet	O
.	O
</s>
<s>
In	O
2012	O
,	O
an	O
incubator	O
for	O
bitcoin-focused	O
start-ups	O
was	O
founded	O
by	O
Adam	O
Draper	O
,	O
with	O
financing	O
help	O
from	O
his	O
father	O
,	O
venture	O
capitalist	O
Tim	O
Draper	O
,	O
one	O
of	O
the	O
largest	O
bitcoin	B-General_Concept
holders	O
after	O
winning	O
an	O
auction	O
of	O
₿30	O
,	O
000	O
,	O
at	O
the	O
time	O
called	O
"	O
mystery	O
buyer	O
"	O
.	O
</s>
<s>
The	O
company	O
's	O
goal	O
is	O
to	O
fund	O
100	O
bitcoin	B-General_Concept
businesses	O
within	O
2	O
–	O
3	O
years	O
with	O
$	O
10,000	O
to	O
$	O
20,000	O
for	O
a	O
6%	O
stake	O
.	O
</s>
<s>
Investors	O
also	O
invest	O
in	O
bitcoin	B-General_Concept
mining	O
.	O
</s>
<s>
According	O
to	O
a	O
2015	O
study	O
by	O
Paolo	O
Tasca	O
,	O
bitcoin	B-General_Concept
startups	O
raised	O
almost	O
$1	O
billion	O
in	O
three	O
years	O
(	O
Q1	O
2012	O
–	O
Q1	O
2015	O
)	O
.	O
</s>
<s>
The	O
price	O
of	O
bitcoins	B-General_Concept
has	O
gone	O
through	O
cycles	O
of	O
appreciation	O
and	O
depreciation	O
referred	O
to	O
by	O
some	O
as	O
bubbles	O
and	O
busts	O
.	O
</s>
<s>
In	O
2011	O
,	O
the	O
value	O
of	O
one	O
bitcoin	B-General_Concept
rapidly	O
rose	O
from	O
about	O
US	O
$0.30	O
to	O
US$32	O
before	O
returning	O
to	O
US$2	O
.	O
</s>
<s>
In	O
the	O
latter	O
half	O
of	O
2012	O
and	O
during	O
the	O
2012	O
–	O
13	O
Cypriot	O
financial	O
crisis	O
,	O
the	O
bitcoin	B-General_Concept
price	O
began	O
to	O
rise	O
,	O
reaching	O
a	O
high	O
of	O
US$266	O
on	O
10	O
April	O
2013	O
,	O
before	O
crashing	O
to	O
around	O
US$50	O
.	O
</s>
<s>
On	O
29	O
November	O
2013	O
,	O
the	O
cost	O
of	O
one	O
bitcoin	B-General_Concept
rose	O
to	O
a	O
peak	O
of	O
US$	O
1,242	O
.	O
</s>
<s>
According	O
to	O
Mark	O
T	O
.	O
Williams	O
,	O
,	O
bitcoin	B-General_Concept
has	O
volatility	O
seven	O
times	O
greater	O
than	O
gold	O
,	O
eight	O
times	O
greater	O
than	O
the	O
S&P	O
500	O
,	O
and	O
18	O
times	O
greater	O
than	O
the	O
US	O
dollar	O
.	O
</s>
<s>
Unusual	O
for	O
an	O
asset	O
,	O
bitcoin	B-General_Concept
weekend	O
trading	O
during	O
December	O
2020	O
was	O
higher	O
than	O
for	O
weekdays	O
.	O
</s>
<s>
,	O
the	O
closing	O
price	O
of	O
bitcoin	B-General_Concept
equaled	O
US$	O
44,797	O
.	O
</s>
<s>
The	O
legal	O
status	O
of	O
bitcoin	B-General_Concept
varies	O
substantially	O
from	O
country	O
to	O
country	O
and	O
is	O
still	O
undefined	O
or	O
changing	O
in	O
many	O
of	O
them	O
.	O
</s>
<s>
Regulations	O
and	O
bans	O
that	O
apply	O
to	O
bitcoin	B-General_Concept
probably	O
extend	O
to	O
similar	O
cryptocurrency	O
systems	O
.	O
</s>
<s>
Because	O
of	O
its	O
decentralized	O
nature	O
and	O
its	O
trading	O
on	O
online	O
exchanges	O
located	O
in	O
many	O
countries	O
,	O
regulation	O
of	O
bitcoin	B-General_Concept
has	O
been	O
difficult	O
.	O
</s>
<s>
However	O
,	O
the	O
use	O
of	O
bitcoin	B-General_Concept
can	O
be	O
criminalized	O
,	O
and	O
shutting	O
down	O
exchanges	O
and	O
the	O
peer-to-peer	O
economy	O
in	O
a	O
given	O
country	O
would	O
constitute	O
a	O
de	O
facto	O
ban	O
.	O
</s>
<s>
On	O
22	O
October	O
2015	O
,	O
the	O
European	O
Court	O
of	O
Justice	O
ruled	O
that	O
bitcoin	B-General_Concept
transactions	O
would	O
be	O
exempt	O
from	O
Value	O
Added	O
Tax	O
.	O
</s>
<s>
The	O
U.S.	O
Commodity	O
Futures	O
Trading	O
Commission	O
has	O
issued	O
four	O
"	O
Customer	O
Advisories	O
"	O
for	O
bitcoin	B-General_Concept
and	O
related	O
investments	O
.	O
</s>
<s>
In	O
May	O
2014	O
the	O
U.S.	O
Securities	O
and	O
Exchange	O
Commission	O
warned	O
that	O
investments	O
involving	O
bitcoin	B-General_Concept
might	O
have	O
high	O
rates	O
of	O
fraud	O
,	O
and	O
that	O
investors	O
might	O
be	O
solicited	O
on	O
social	O
media	O
sites	O
.	O
</s>
<s>
An	O
earlier	O
"	O
Investor	O
Alert	O
"	O
warned	O
about	O
the	O
use	O
of	O
bitcoin	B-General_Concept
in	O
Ponzi	O
schemes	O
.	O
</s>
<s>
The	O
European	O
Banking	O
Authority	O
issued	O
a	O
warning	O
in	O
2013	O
focusing	O
on	O
the	O
lack	O
of	O
regulation	O
of	O
bitcoin	B-General_Concept
,	O
the	O
chance	O
that	O
exchanges	O
would	O
be	O
hacked	O
,	O
the	O
volatility	O
of	O
bitcoin	B-General_Concept
's	O
price	O
,	O
and	O
general	O
fraud	O
.	O
</s>
<s>
FINRA	O
and	O
the	O
North	O
American	O
Securities	O
Administrators	O
Association	O
have	O
both	O
issued	O
investor	O
alerts	O
about	O
bitcoin	B-General_Concept
.	O
</s>
<s>
An	O
official	O
investigation	O
into	O
bitcoin	B-General_Concept
traders	O
was	O
reported	O
in	O
May	O
2018	O
.	O
</s>
<s>
The	O
final	O
settlement	O
price	O
of	O
CME	O
bitcoin	B-General_Concept
futures	O
is	O
determined	O
by	O
prices	O
on	O
four	O
exchanges	O
,	O
Bitstamp	B-Protocol
,	O
Coinbase	O
,	O
itBit	O
and	O
Kraken	O
.	O
</s>
<s>
State	O
and	O
provincial	O
securities	O
regulators	O
,	O
coordinated	O
through	O
the	O
North	O
American	O
Securities	O
Administrators	O
Association	O
,	O
are	O
investigating	O
"	O
bitcoin	B-Architecture
scams	I-Architecture
"	O
and	O
ICOs	B-Application
in	O
40	O
jurisdictions	O
.	O
</s>
<s>
Academic	O
research	O
published	O
in	O
the	O
Journal	O
of	O
Monetary	O
Economics	O
concluded	O
that	O
price	O
manipulation	O
occurred	O
during	O
the	O
Mt	B-General_Concept
Gox	I-General_Concept
bitcoin	B-General_Concept
theft	O
and	O
that	O
the	O
market	O
remains	O
vulnerable	O
to	O
manipulation	O
.	O
</s>
<s>
The	O
history	O
of	O
hacks	O
,	O
fraud	O
and	O
theft	O
involving	O
bitcoin	B-General_Concept
dates	O
back	O
to	O
at	O
least	O
2011	O
.	O
</s>
<s>
Research	O
by	O
John	O
M	O
.	O
Griffin	O
and	O
Amin	O
Shams	O
in	O
2018	O
suggests	O
that	O
trading	O
associated	O
with	O
increases	O
in	O
the	O
amount	O
of	O
the	O
Tether	B-Application
cryptocurrency	I-Application
and	O
associated	O
trading	O
at	O
the	O
Bitfinex	B-Protocol
exchange	O
account	O
for	O
about	O
half	O
of	O
the	O
price	O
increase	O
in	O
bitcoin	B-General_Concept
in	O
late	O
2017	O
.	O
</s>
<s>
van	O
der	O
Velde	O
,	O
CEO	O
of	O
both	O
Bitfinex	B-Protocol
and	O
Tether	B-Application
,	O
denied	O
the	O
claims	O
of	O
price	O
manipulation	O
:	O
"	O
Bitfinex	B-Protocol
nor	O
Tether	B-Application
is	O
,	O
or	O
has	O
ever	O
,	O
engaged	O
in	O
any	O
sort	O
of	O
market	O
or	O
price	O
manipulation	O
.	O
</s>
<s>
Tether	B-Application
issuances	O
cannot	O
be	O
used	O
to	O
prop	O
up	O
the	O
price	O
of	O
bitcoin	B-General_Concept
or	O
any	O
other	O
coin/token	O
on	O
Bitfinex.	O
"	O
</s>
<s>
In	O
June	O
2021	O
,	O
the	O
Legislative	O
Assembly	O
of	O
El	O
Salvador	O
voted	O
legislation	O
to	O
make	O
bitcoin	B-General_Concept
legal	O
tender	O
in	O
El	O
Salvador	O
,	O
alongside	O
the	O
US	O
dollar	O
.	O
</s>
<s>
According	O
to	O
a	O
survey	O
by	O
the	O
Central	O
American	O
University	O
,	O
the	O
majority	O
of	O
Salvadorans	O
disagreed	O
with	O
using	O
cryptocurrency	O
as	O
a	O
legal	O
tender	O
,	O
and	O
a	O
survey	O
by	O
the	O
Center	O
for	O
Citizen	O
Studies	O
(	O
CEC	O
)	O
showed	O
that	O
91%	O
of	O
the	O
country	O
prefers	O
the	O
dollar	O
over	O
bitcoin	B-General_Concept
.	O
</s>
<s>
As	O
of	O
October	O
2021	O
,	O
the	O
country	O
's	O
government	O
was	O
exploring	O
mining	O
bitcoin	B-General_Concept
with	O
geothermal	O
power	O
and	O
issuing	O
bonds	O
tied	O
to	O
bitcoin	B-General_Concept
.	O
</s>
<s>
According	O
to	O
a	O
survey	O
done	O
by	O
the	O
Central	O
American	O
University	O
100	O
days	O
after	O
the	O
Bitcoin	B-General_Concept
Law	O
came	O
into	O
force	O
:	O
34.8	O
%	O
of	O
the	O
population	O
has	O
no	O
confidence	O
in	O
bitcoin	B-General_Concept
,	O
35.3	O
%	O
has	O
little	O
confidence	O
,	O
13.2	O
%	O
has	O
some	O
confidence	O
,	O
and	O
14.1	O
%	O
has	O
a	O
lot	O
of	O
confidence	O
.	O
</s>
<s>
56.6	O
%	O
of	O
respondents	O
have	O
downloaded	O
the	O
government	O
bitcoin	B-General_Concept
wallet	O
;	O
among	O
them	O
62.9	O
%	O
has	O
never	O
used	O
it	O
or	O
only	O
once	O
whereas	O
36.3	O
%	O
uses	O
bitcoin	B-General_Concept
at	O
least	O
once	O
a	O
month	O
.	O
</s>
<s>
In	O
2022	O
,	O
the	O
International	O
Monetary	O
Fund	O
(	O
IMF	O
)	O
urged	O
El	O
Salvador	O
to	O
reverse	O
its	O
decision	O
after	O
bitcoin	B-General_Concept
lost	O
half	O
its	O
value	O
in	O
two	O
months	O
.	O
</s>
<s>
According	O
to	O
one	O
report	O
in	O
2022	O
,	O
80%	O
of	O
businesses	O
refused	O
to	O
accept	O
bitcoin	B-General_Concept
despite	O
being	O
legally	O
required	O
to	O
.	O
</s>
<s>
In	O
April	O
2022	O
,	O
the	O
Central	O
African	O
Republic	O
(	O
CAR	O
)	O
adopted	O
Bitcoin	B-General_Concept
as	O
legal	O
tender	O
alongside	O
the	O
CFA	O
franc	O
.	O
</s>
<s>
Ukraine	O
is	O
accepting	O
donations	O
in	O
cryptocurrency	O
,	O
including	O
bitcoin	B-General_Concept
,	O
to	O
fund	O
the	O
resistance	O
against	O
the	O
Russian	O
invasion	O
.	O
</s>
<s>
In	O
the	O
same	O
month	O
,	O
a	O
cryptocurrency	O
exchange	O
was	O
integrated	O
into	O
the	O
Ukrainian	O
e-governance	O
service	O
Diia	B-Application
.	O
</s>
<s>
Iran	O
announced	O
pending	O
regulations	O
that	O
would	O
require	O
bitcoin	B-General_Concept
miners	O
in	O
Iran	O
to	O
sell	O
bitcoin	B-General_Concept
to	O
the	O
Central	O
Bank	O
of	O
Iran	O
,	O
and	O
the	O
central	O
bank	O
would	O
use	O
it	O
for	O
imports	O
.	O
</s>
<s>
Iran	O
,	O
as	O
of	O
October	O
2020	O
,	O
had	O
issued	O
over	O
1,000	O
bitcoin	B-General_Concept
mining	O
licenses	O
.	O
</s>
<s>
The	O
US	O
Office	O
of	O
Foreign	O
Assets	O
Control	O
listed	O
two	O
Iranians	O
and	O
their	O
bitcoin	B-General_Concept
addresses	O
as	O
part	O
of	O
its	O
Specially	O
Designated	O
Nationals	O
and	O
Blocked	O
Persons	O
List	O
for	O
their	O
role	O
in	O
the	O
2018	O
Atlanta	O
cyberattack	O
whose	O
ransom	O
was	O
paid	O
in	O
bitcoin	B-General_Concept
.	O
</s>
<s>
Some	O
constituent	O
states	O
accept	O
tax	O
payments	O
in	O
bitcoin	B-General_Concept
,	O
including	O
Colorado	O
(	O
US	O
)	O
and	O
Zug	O
(	O
Switzerland	B-Protocol
)	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
,	O
along	O
with	O
other	O
cryptocurrencies	O
,	O
has	O
been	O
described	O
as	O
an	O
economic	O
bubble	O
by	O
at	O
least	O
eight	O
Nobel	O
Memorial	O
Prize	O
in	O
Economic	O
Sciences	O
laureates	O
,	O
including	O
Robert	O
Shiller	O
,	O
Joseph	O
Stiglitz	O
,	O
and	O
Richard	O
Thaler	O
.	O
</s>
<s>
Economist	O
and	O
columnist	O
Paul	O
Krugman	O
has	O
described	O
bitcoin	B-General_Concept
as	O
"	O
a	O
bubble	O
wrapped	O
in	O
techno-mysticism	O
inside	O
a	O
cocoon	O
of	O
libertarian	O
ideology	O
"	O
,	O
economist	O
Nouriel	O
Roubini	O
of	O
New	O
York	O
University	O
has	O
called	O
bitcoin	B-General_Concept
the	O
"	O
mother	O
of	O
all	O
bubbles	O
"	O
,	O
and	O
University	O
of	O
Chicago	O
economist	O
James	O
Heckman	O
has	O
compared	O
it	O
to	O
the	O
17th-century	O
tulip	O
mania	O
.	O
</s>
<s>
Journalists	O
,	O
economists	O
,	O
investors	O
,	O
and	O
the	O
central	O
bank	O
of	O
Estonia	O
have	O
voiced	O
concerns	O
that	O
bitcoin	B-General_Concept
is	O
a	O
Ponzi	O
scheme	O
.	O
</s>
<s>
Eric	O
Posner	O
,	O
a	O
law	O
professor	O
at	O
the	O
University	O
of	O
Chicago	O
,	O
states	O
that	O
"	O
a	O
real	O
Ponzi	O
scheme	O
takes	O
fraud	O
;	O
bitcoin	B-General_Concept
,	O
by	O
contrast	O
,	O
seems	O
more	O
like	O
a	O
collective	O
delusion.	O
"	O
</s>
<s>
A	O
2014	O
report	O
by	O
the	O
World	O
Bank	O
concluded	O
that	O
bitcoin	B-General_Concept
was	O
not	O
a	O
deliberate	O
Ponzi	O
scheme	O
.	O
</s>
<s>
Also	O
in	O
2014	O
,	O
the	O
Swiss	O
Federal	O
Council	O
examined	O
concerns	O
that	O
bitcoin	B-General_Concept
might	O
be	O
a	O
pyramid	O
scheme	O
,	O
and	O
concluded	O
that	O
"	O
since	O
in	O
the	O
case	O
of	O
bitcoin	B-General_Concept
the	O
typical	O
promises	O
of	O
profits	O
are	O
lacking	O
,	O
it	O
cannot	O
be	O
assumed	O
that	O
bitcoin	B-General_Concept
is	O
a	O
pyramid	O
scheme.	O
"	O
</s>
<s>
Bitcoin	B-General_Concept
wealth	O
is	O
highly	O
concentrated	O
,	O
with	O
0.01	O
%	O
holding	O
27%	O
of	O
in-circulation	O
currency	O
,	O
as	O
of	O
2021	O
.	O
</s>
<s>
The	O
use	O
of	O
bitcoin	B-General_Concept
by	O
criminals	O
has	O
attracted	O
the	O
attention	O
of	O
financial	O
regulators	O
,	O
legislative	O
bodies	O
,	O
law	O
enforcement	O
,	O
and	O
the	O
media	O
.	O
</s>
<s>
Several	O
news	O
outlets	O
have	O
asserted	O
that	O
the	O
popularity	O
of	O
bitcoins	B-General_Concept
hinges	O
on	O
the	O
ability	O
to	O
use	O
them	O
to	O
purchase	O
illegal	O
goods	O
.	O
</s>
<s>
Nobel-prize	O
winning	O
economist	O
Joseph	O
Stiglitz	O
says	O
that	O
bitcoin	B-General_Concept
's	O
anonymity	O
encourages	O
money	O
laundering	O
and	O
other	O
crimes	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
Core	O
is	O
free	B-License
and	I-License
open-source	I-License
software	I-License
that	O
serves	O
as	O
a	O
bitcoin	B-General_Concept
node	B-Protocol
(	O
the	O
set	O
of	O
which	O
form	O
the	O
bitcoin	B-General_Concept
network	I-General_Concept
)	O
and	O
provides	O
a	O
bitcoin	B-General_Concept
wallet	O
which	O
fully	O
verifies	O
payments	O
.	O
</s>
<s>
It	O
is	O
considered	O
to	O
be	O
bitcoin	B-General_Concept
's	O
reference	O
implementation	O
.	O
</s>
<s>
Initially	O
,	O
the	O
software	O
was	O
published	O
by	O
Satoshi	O
Nakamoto	O
under	O
the	O
name	O
"	O
Bitcoin	B-General_Concept
"	O
,	O
and	O
later	O
renamed	O
to	O
"	O
Bitcoin	B-General_Concept
Core	O
"	O
to	O
distinguish	O
it	O
from	O
the	O
network	B-General_Concept
.	O
</s>
<s>
The	O
MIT	O
Digital	O
Currency	O
Initiative	O
funds	O
some	O
of	O
the	O
development	O
of	O
Bitcoin	B-General_Concept
Core	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
Core	O
includes	O
a	O
transaction	O
verification	O
engine	O
and	O
connects	O
to	O
the	O
bitcoin	B-General_Concept
network	I-General_Concept
as	O
a	O
full	O
node	B-Protocol
.	O
</s>
<s>
Moreover	O
,	O
a	O
cryptocurrency	B-Protocol
wallet	I-Protocol
,	O
which	O
can	O
be	O
used	O
to	O
transfer	O
funds	O
,	O
is	O
included	O
by	O
default	O
.	O
</s>
<s>
The	O
wallet	O
allows	O
for	O
the	O
sending	O
and	O
receiving	O
of	O
bitcoins	B-General_Concept
.	O
</s>
<s>
It	O
does	O
not	O
facilitate	O
the	O
buying	O
or	O
selling	O
of	O
bitcoin	B-General_Concept
.	O
</s>
<s>
The	O
software	O
validates	O
the	O
entire	O
blockchain	B-Application
,	O
which	O
includes	O
all	O
bitcoin	B-General_Concept
transactions	O
ever	O
.	O
</s>
<s>
This	O
distributed	O
ledger	B-Language
which	O
has	O
reached	O
more	O
than	O
235	O
gigabytes	O
in	O
size	O
as	O
of	O
Jan	O
2019	O
,	O
must	O
be	O
downloaded	O
or	O
synchronized	O
before	O
full	O
participation	O
of	O
the	O
client	O
may	O
occur	O
.	O
</s>
<s>
Although	O
the	O
complete	O
blockchain	B-Application
is	O
not	O
needed	O
all	O
at	O
once	O
since	O
it	O
is	O
possible	O
to	O
run	O
in	O
pruning	O
mode	O
.	O
</s>
<s>
A	O
command	O
line-based	O
daemon	B-Operating_System
with	O
a	O
JSON-RPC	B-General_Concept
interface	O
,	O
bitcoind	B-Protocol
,	O
is	O
bundled	O
with	O
Bitcoin	B-General_Concept
Core	O
.	O
</s>
<s>
It	O
also	O
provides	O
access	O
to	O
testnet	O
,	O
a	O
global	O
testing	O
environment	O
that	O
imitates	O
the	O
bitcoin	B-General_Concept
main	O
network	B-General_Concept
using	O
an	O
alternative	O
blockchain	B-Application
where	O
valueless	O
"	O
test	O
bitcoins	B-General_Concept
"	O
are	O
used	O
.	O
</s>
<s>
Regtest	O
or	O
Regression	O
Test	O
Mode	O
creates	O
a	O
private	O
blockchain	B-Application
which	O
is	O
used	O
as	O
a	O
local	O
testing	O
environment	O
.	O
</s>
<s>
Finally	O
,	O
bitcoin-cli	O
,	O
a	O
simple	O
program	O
which	O
allows	O
users	O
to	O
send	O
RPC	B-Operating_System
commands	O
to	O
bitcoind	B-Protocol
,	O
is	O
also	O
included	O
.	O
</s>
<s>
Checkpoints	O
which	O
have	O
been	O
hard	O
coded	O
into	O
the	O
client	O
are	O
used	O
only	O
to	O
prevent	O
Denial	O
of	O
Service	O
attacks	O
against	O
nodes	B-Protocol
which	O
are	O
initially	O
syncing	O
the	O
chain	O
.	O
</s>
<s>
This	O
limited	O
the	O
maximum	O
network	B-General_Concept
capacity	O
to	O
about	O
three	O
transactions	O
per	O
second	O
.	O
</s>
<s>
Since	O
then	O
,	O
network	B-General_Concept
capacity	O
has	O
been	O
improved	O
incrementally	O
both	O
through	O
block	O
size	O
increases	O
and	O
improved	O
wallet	O
behavior	O
.	O
</s>
<s>
A	O
network	B-General_Concept
alert	O
system	O
was	O
included	O
by	O
Satoshi	O
Nakamoto	O
as	O
a	O
way	O
of	O
informing	O
users	O
of	O
important	O
news	O
regarding	O
bitcoin	B-General_Concept
.	O
</s>
<s>
It	O
had	O
become	O
obsolete	O
as	O
news	O
on	O
bitcoin	B-General_Concept
is	O
now	O
widely	O
disseminated	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
Core	O
includes	O
a	O
scripting	O
language	O
inspired	O
by	O
Forth	B-Application
that	O
can	O
define	O
transactions	O
and	O
specify	O
parameters	O
.	O
</s>
<s>
Operations	B-General_Concept
on	O
the	O
data	O
are	O
performed	O
by	O
various	O
OP_Codes	O
.	O
</s>
<s>
Two	O
stacks	B-Application
are	O
used	O
–	O
main	O
and	O
alt	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
Core	O
uses	O
OpenTimestamps	B-General_Concept
to	O
timestamp	O
merge	O
commits	O
.	O
</s>
<s>
The	O
original	O
creator	O
of	O
the	O
bitcoin	B-General_Concept
client	O
has	O
described	O
their	O
approach	O
to	O
the	O
software	O
's	O
authorship	O
as	O
it	O
being	O
written	O
first	O
to	O
prove	O
to	O
themselves	O
that	O
the	O
concept	O
of	O
purely	O
peer-to-peer	O
electronic	O
cash	O
was	O
valid	O
and	O
that	O
a	O
paper	O
with	O
solutions	O
could	O
be	O
written	O
.	O
</s>
<s>
Andresen	O
left	O
the	O
role	O
of	O
lead	O
developer	O
for	O
bitcoin	B-General_Concept
to	O
work	O
on	O
the	O
strategic	O
development	O
of	O
its	O
technology	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
Core	O
in	O
2015	O
was	O
central	O
to	O
a	O
dispute	O
with	O
Bitcoin	B-Protocol
XT	I-Protocol
,	O
a	O
competing	O
client	O
that	O
sought	O
to	O
increase	O
the	O
blocksize	O
.	O
</s>
<s>
Over	O
a	O
dozen	O
different	O
companies	O
and	O
industry	O
groups	O
fund	O
the	O
development	O
of	O
Bitcoin	B-General_Concept
Core	O
.	O
</s>
<s>
It	O
originated	O
in	O
a	O
December	O
2013	O
post	O
on	O
the	O
Bitcoin	B-General_Concept
Forum	O
message	O
board	O
by	O
an	O
apparently	O
inebriated	O
user	O
who	O
posted	O
with	O
a	O
typo	O
in	O
the	O
subject	O
,	O
"	O
I	O
AM	O
HODLING.	O
"	O
</s>
<s>
In	O
2017	O
,	O
Quartz	O
listed	O
it	O
as	O
one	O
of	O
the	O
essential	O
slang	O
terms	O
in	O
bitcoin	B-General_Concept
culture	O
,	O
and	O
described	O
it	O
as	O
a	O
stance	O
,	O
"	O
to	O
stay	O
invested	O
in	O
bitcoin	B-General_Concept
and	O
not	O
to	O
capitulate	O
in	O
the	O
face	O
of	O
plunging	O
prices.	O
"	O
</s>
<s>
TheStreet.com	O
referred	O
to	O
it	O
as	O
the	O
"	O
favorite	O
mantra	O
"	O
of	O
bitcoin	B-General_Concept
holders	O
.	O
</s>
<s>
In	O
Charles	O
Stross	O
's	O
2013	O
science	O
fiction	O
novel	O
Neptune	O
's	O
Brood	O
,	O
the	O
universal	O
interstellar	O
payment	O
system	O
is	O
known	O
as	O
"	O
bitcoin	B-General_Concept
"	O
and	O
operates	O
using	O
cryptography	O
.	O
</s>
<s>
Bitcoin	B-General_Concept
was	O
obscure	O
back	O
then	O
,	O
and	O
I	O
figured	O
had	O
just	O
enough	O
name	O
recognition	O
to	O
be	O
a	O
useful	O
term	O
for	O
an	O
interstellar	O
currency	O
:	O
it	O
'd	O
clue	O
people	O
in	O
that	O
it	O
was	O
a	O
networked	O
digital	O
currency.	O
"	O
</s>
<s>
The	O
2014	O
documentary	O
The	O
Rise	O
and	O
Rise	O
of	O
Bitcoin	B-General_Concept
portrays	O
the	O
diversity	O
of	O
motives	O
behind	O
the	O
use	O
of	O
bitcoin	B-General_Concept
by	O
interviewing	O
people	O
who	O
use	O
it	O
.	O
</s>
<s>
The	O
2016	O
documentary	O
Banking	O
on	O
Bitcoin	B-General_Concept
is	O
an	O
introduction	O
to	O
the	O
beginnings	O
of	O
bitcoin	B-General_Concept
and	O
the	O
ideas	O
behind	O
cryptocurrency	O
today	O
.	O
</s>
<s>
In	O
September	O
2015	O
,	O
the	O
establishment	O
of	O
the	O
peer-reviewed	O
academic	O
journal	O
Ledger	B-Language
(	O
)	O
was	O
announced	O
.	O
</s>
<s>
The	O
journal	O
encourages	O
authors	O
to	O
digitally	O
sign	O
a	O
file	B-Error_Name
hash	I-Error_Name
of	O
submitted	O
papers	O
,	O
which	O
will	O
then	O
be	O
timestamped	O
into	O
the	O
bitcoin	B-General_Concept
blockchain	B-Application
.	O
</s>
<s>
Authors	O
are	O
also	O
asked	O
to	O
include	O
a	O
personal	O
bitcoin	B-General_Concept
address	O
in	O
the	O
first	O
page	O
of	O
their	O
papers	O
.	O
</s>
