<s>
Ethereum	B-Application
is	O
a	O
decentralized	O
blockchain	B-Application
with	O
smart	B-Application
contract	I-Application
functionality	O
.	O
</s>
<s>
Ether	B-Application
(	O
Abbreviation	O
:	O
ETH	O
;	O
sign	O
:	O
Ξ	O
)	O
is	O
the	O
native	O
cryptocurrency	O
of	O
the	O
platform	O
.	O
</s>
<s>
Among	O
cryptocurrencies	O
,	O
ether	B-Application
is	O
second	O
only	O
to	O
bitcoin	B-Protocol
in	O
market	O
capitalization	O
.	O
</s>
<s>
It	O
is	O
open-source	B-Application
software	I-Application
.	O
</s>
<s>
Ethereum	B-Application
was	O
conceived	O
in	O
2013	O
by	O
programmer	O
Vitalik	O
Buterin	O
.	O
</s>
<s>
Additional	O
founders	O
of	O
Ethereum	B-Application
included	O
Gavin	O
Wood	O
,	O
Charles	O
Hoskinson	O
,	O
Anthony	O
Di	O
Iorio	O
and	O
Joseph	O
Lubin	O
.	O
</s>
<s>
Ethereum	B-Application
allows	O
anyone	O
to	O
deploy	O
permanent	O
and	O
immutable	O
decentralized	B-Application
applications	I-Application
onto	O
it	O
,	O
with	O
which	O
users	O
can	O
interact	O
.	O
</s>
<s>
Decentralized	B-Protocol
finance	I-Protocol
(	O
DeFi	B-Protocol
)	O
applications	O
provide	O
financial	O
instruments	O
which	O
do	O
not	O
directly	O
rely	O
on	O
financial	O
intermediaries	O
like	O
brokerages	O
,	O
exchanges	O
,	O
or	O
banks	O
.	O
</s>
<s>
Ethereum	B-Application
also	O
allows	O
users	O
to	O
create	O
and	O
exchange	O
non-fungible	O
tokens	O
(	O
NFTs	O
)	O
,	O
which	O
are	O
tokens	O
that	O
can	O
be	O
tied	O
to	O
unique	O
digital	O
assets	O
,	O
such	O
as	O
images	O
.	O
</s>
<s>
Additionally	O
,	O
many	O
other	O
cryptocurrencies	O
utilize	O
the	O
ERC-20	O
token	O
standard	O
on	O
top	O
of	O
the	O
Ethereum	B-Application
blockchain	B-Application
and	O
have	O
utilized	O
the	O
platform	O
for	O
initial	B-Application
coin	I-Application
offerings	I-Application
.	O
</s>
<s>
On	O
15	O
September	O
2022	O
,	O
Ethereum	B-Application
transitioned	O
its	O
consensus	B-Operating_System
mechanism	I-Operating_System
from	O
proof-of-work	O
(	O
PoW	O
)	O
to	O
proof-of-stake	B-Protocol
(	O
PoS	O
)	O
in	O
an	O
upgrade	O
process	O
known	O
as	O
"	O
the	O
Merge	O
"	O
.	O
</s>
<s>
This	O
has	O
cut	O
Ethereum	B-Application
's	O
energy	O
usage	O
by	O
99%	O
.	O
</s>
<s>
Ethereum	B-Application
was	O
initially	O
described	O
in	O
late	O
2013	O
in	O
a	O
white	O
paper	O
by	O
Vitalik	O
Buterin	O
,	O
a	O
programmer	O
and	O
co-founder	O
of	O
Bitcoin	B-Protocol
Magazine	O
,	O
that	O
described	O
a	O
way	O
to	O
build	O
decentralized	B-Application
applications	I-Application
.	O
</s>
<s>
Buterin	O
argued	O
to	O
the	O
Bitcoin	B-Language
Core	I-Language
developers	O
that	O
Bitcoin	B-Protocol
and	O
blockchain	B-Application
technology	I-Application
could	O
benefit	O
from	O
other	O
applications	O
besides	O
money	O
and	O
that	O
it	O
needed	O
a	O
more	O
robust	O
language	O
for	O
application	O
development	O
that	O
could	O
lead	O
to	O
real-world	O
assets	O
,	O
such	O
as	O
stocks	O
and	O
property	O
,	O
to	O
the	O
blockchain	B-Application
.	O
</s>
<s>
In	O
2013	O
,	O
Buterin	O
briefly	O
worked	O
with	O
eToro	O
CEO	O
Yoni	O
Assia	O
on	O
the	O
Colored	B-Protocol
Coins	I-Protocol
project	O
and	O
drafted	O
its	O
white	O
paper	O
outlining	O
additional	O
use	O
cases	O
for	O
blockchain	B-Application
technology	I-Application
.	O
</s>
<s>
However	O
,	O
after	O
failing	O
to	O
gain	O
agreement	O
on	O
how	O
the	O
project	O
should	O
proceed	O
,	O
he	O
proposed	O
the	O
development	O
of	O
a	O
new	O
platform	O
with	O
a	O
more	O
robust	O
scripting	O
language	O
—	O
a	O
Turing-complete	B-Algorithm
programming	O
language	O
—	O
that	O
would	O
eventually	O
become	O
Ethereum	B-Application
.	O
</s>
<s>
Ethereum	B-Application
was	O
announced	O
at	O
the	O
North	O
American	O
Bitcoin	B-Protocol
Conference	O
in	O
Miami	O
,	O
in	O
January	O
2014	O
.	O
</s>
<s>
During	O
the	O
conference	O
,	O
Gavin	O
Wood	O
,	O
Charles	O
Hoskinson	O
,	O
and	O
Anthony	O
Di	O
Iorio	O
(	O
who	O
financed	O
the	O
project	O
)	O
rented	O
a	O
house	O
in	O
Miami	O
with	O
Buterin	O
at	O
which	O
they	O
could	O
develop	O
a	O
fuller	O
sense	O
of	O
what	O
Ethereum	B-Application
might	O
become	O
.	O
</s>
<s>
Hoskinson	O
left	O
the	O
project	O
at	O
that	O
time	O
and	O
soon	O
after	O
founded	O
IOHK	O
,	O
a	O
blockchain	B-Operating_System
company	I-Operating_System
responsible	O
for	O
Cardano	B-Protocol
.	O
</s>
<s>
Ethereum	B-Application
has	O
an	O
unusually	O
long	O
list	O
of	O
founders	O
.	O
</s>
<s>
Anthony	O
Di	O
Iorio	O
wrote	O
:	O
"	O
Ethereum	B-Application
was	O
founded	O
by	O
Vitalik	O
Buterin	O
,	O
Myself	O
,	O
Charles	O
Hoskinson	O
,	O
Mihai	O
Alisie	O
&	O
Amir	O
Chetrit	O
(	O
the	O
initial	O
5	O
)	O
in	O
December	O
2013	O
.	O
</s>
<s>
Buterin	O
chose	O
the	O
name	O
Ethereum	B-Application
after	O
browsing	O
a	O
list	O
of	O
elements	O
from	O
science	O
fiction	O
on	O
Wikipedia	O
.	O
</s>
<s>
He	O
stated	O
,	O
"	O
I	O
immediately	O
realized	O
that	O
I	O
liked	O
it	O
better	O
than	O
all	O
of	O
the	O
other	O
alternatives	O
that	O
I	O
had	O
seen	O
;	O
I	O
suppose	O
it	O
was	O
the	O
fact	O
that	O
 [ it ] 	O
sounded	O
nice	O
and	O
it	O
had	O
the	O
word	O
'	O
ether	B-Application
 '	O
,	O
referring	O
to	O
the	O
hypothetical	O
invisible	O
medium	O
that	O
permeates	O
the	O
universe	O
and	O
allows	O
light	O
to	O
travel.	O
"	O
</s>
<s>
Formal	O
development	O
of	O
the	O
software	O
underlying	O
Ethereum	B-Application
began	O
in	O
early	O
2014	O
through	O
a	O
Swiss	O
company	O
,	O
Ethereum	B-Application
Switzerland	O
GmbH	O
(	O
EthSuisse	O
)	O
.	O
</s>
<s>
The	O
idea	O
of	O
putting	O
executable	O
smart	B-Application
contracts	I-Application
in	O
the	O
blockchain	B-Application
needed	O
to	O
be	O
specified	O
before	O
it	O
could	O
be	O
implemented	O
in	O
software	O
.	O
</s>
<s>
This	O
work	O
was	O
done	O
by	O
Gavin	O
Wood	O
,	O
then	O
the	O
chief	O
technology	O
officer	O
,	O
in	O
the	O
Ethereum	B-Application
Yellow	O
Paper	O
that	O
specified	O
the	O
Ethereum	B-Application
Virtual	O
Machine	O
.	O
</s>
<s>
Subsequently	O
,	O
a	O
Swiss	O
non-profit	O
foundation	O
,	O
the	O
Ethereum	B-Application
Foundation	I-Application
(	O
Stiftung	B-Application
Ethereum	I-Application
)	O
,	O
was	O
founded	O
.	O
</s>
<s>
Development	O
was	O
funded	O
by	O
an	O
online	O
public	O
crowd	B-Application
sale	I-Application
from	O
July	O
to	O
August	O
2014	O
,	O
in	O
which	O
participants	O
bought	O
the	O
Ethereum	B-Application
value	O
token	O
(	O
ether	B-Application
)	O
with	O
another	O
digital	O
currency	O
,	O
bitcoin	B-Protocol
.	O
</s>
<s>
While	O
there	O
was	O
early	O
praise	O
for	O
the	O
technical	O
innovations	O
of	O
Ethereum	B-Application
,	O
questions	O
were	O
also	O
raised	O
about	O
its	O
security	O
and	O
scalability	O
.	O
</s>
<s>
+	O
Ethereum	B-Application
protocol	O
upgrades	O
Protocol	O
layer	O
Code	B-Application
name	O
Release	O
date	O
Block	O
no	O
.	O
</s>
<s>
Several	O
codenamed	O
prototypes	O
of	O
Ethereum	B-Application
were	O
developed	O
over	O
18	O
months	O
in	O
2014	O
and	O
2015	O
by	O
the	O
Ethereum	B-Application
Foundation	I-Application
as	O
part	O
of	O
their	O
proof-of-concept	O
series	O
.	O
</s>
<s>
The	O
Olympic	O
network	O
gave	O
users	O
a	O
bug	O
bounty	O
of	O
25,000	O
ether	B-Application
for	O
stress-testing	O
the	O
Ethereum	B-Application
blockchain	B-Application
.	O
</s>
<s>
On	O
30	O
July	O
2015	O
,	O
"	O
Frontier	O
"	O
marked	O
the	O
official	O
launch	O
of	O
the	O
Ethereum	B-Application
platform	O
,	O
and	O
Ethereum	B-Application
created	O
its	O
"	O
genesis	O
block	O
"	O
.	O
</s>
<s>
The	O
genesis	O
block	O
contained	O
8,893	O
transactions	O
allocating	O
various	O
amounts	O
of	O
ether	B-Application
to	O
different	O
addresses	O
,	O
and	O
a	O
block	O
reward	O
of	O
5	O
ETH	O
.	O
</s>
<s>
Since	O
the	O
initial	O
launch	O
,	O
Ethereum	B-Application
has	O
undergone	O
a	O
number	O
of	O
planned	O
protocol	O
upgrades	O
,	O
which	O
are	O
important	O
changes	O
affecting	O
the	O
underlying	O
functionality	O
and/or	O
incentive	O
structures	O
of	O
the	O
platform	O
.	O
</s>
<s>
In	O
2016	O
,	O
a	O
decentralized	B-Operating_System
autonomous	I-Operating_System
organization	I-Operating_System
called	O
The	B-Protocol
DAO	I-Protocol
—	O
a	O
set	O
of	O
smart	B-Application
contracts	I-Application
developed	O
on	O
the	O
platform	O
—	O
raised	O
a	O
record	O
in	O
a	O
crowd	B-Application
sale	I-Application
to	O
fund	O
the	O
project	O
.	O
</s>
<s>
The	B-Protocol
DAO	I-Protocol
was	O
exploited	O
in	O
June	O
2016	O
when	O
of	O
DAO	O
tokens	O
were	O
stolen	O
by	O
an	O
unknown	O
hacker	O
.	O
</s>
<s>
The	O
event	O
sparked	O
a	O
debate	O
in	O
the	O
crypto-community	O
about	O
whether	O
Ethereum	B-Application
should	O
perform	O
a	O
contentious	O
"	O
hard	O
fork	O
"	O
to	O
reappropriate	O
the	O
affected	O
funds	O
.	O
</s>
<s>
The	O
fork	O
resulted	O
in	O
the	O
network	O
splitting	O
into	O
two	O
blockchains	B-Application
:	O
Ethereum	B-Application
with	O
the	O
theft	O
reversed	O
,	O
and	O
Ethereum	B-Protocol
Classic	I-Protocol
which	O
continued	O
on	O
the	O
original	O
chain	O
.	O
</s>
<s>
In	O
March	O
2017	O
,	O
various	O
blockchain	B-Application
startups	O
,	O
research	O
groups	O
,	O
and	O
Fortune	O
500	O
companies	O
announced	O
the	O
creation	O
of	O
the	O
Enterprise	O
Ethereum	B-Application
Alliance	O
(	O
EEA	O
)	O
with	O
30	O
founding	O
members	O
.	O
</s>
<s>
By	O
January	O
2018	O
,	O
ether	B-Application
was	O
the	O
second-largest	O
cryptocurrency	O
in	O
terms	O
of	O
market	O
capitalization	O
,	O
behind	O
bitcoin	B-Protocol
.	O
</s>
<s>
In	O
2019	O
,	O
Ethereum	B-Application
Foundation	I-Application
employee	O
Virgil	O
Griffith	O
was	O
arrested	O
by	O
the	O
US	O
government	O
for	O
presenting	O
at	O
a	O
blockchain	B-Application
conference	O
in	O
North	O
Korea	O
.	O
</s>
<s>
In	O
March	O
2021	O
,	O
Visa	O
Inc	O
.	O
announced	O
that	O
it	O
began	O
settling	O
stablecoin	B-Protocol
transactions	O
using	O
Ethereum	B-Application
.	O
</s>
<s>
In	O
April	O
2021	O
,	O
JP	O
Morgan	O
Chase	O
,	O
UBS	O
,	O
and	O
MasterCard	O
announced	O
that	O
they	O
were	O
investing	O
into	O
ConsenSys	O
,	O
a	O
software	O
development	O
firm	O
that	O
builds	O
Ethereum-related	O
infrastructure	O
.	O
</s>
<s>
The	O
London	O
upgrade	O
included	O
Ethereum	B-Application
Improvement	O
Proposal	O
(	O
"	O
EIP	O
"	O
)	O
1559	O
,	O
a	O
mechanism	O
for	O
reducing	O
transaction	O
fee	O
volatility	O
.	O
</s>
<s>
The	O
mechanism	O
causes	O
a	O
portion	O
of	O
the	O
ether	B-Application
paid	O
in	O
transaction	O
fees	O
for	O
each	O
block	O
to	O
be	O
destroyed	O
rather	O
than	O
given	O
to	O
the	O
block	O
proposer	O
,	O
reducing	O
the	O
inflation	O
rate	O
of	O
ether	B-Application
and	O
potentially	O
resulting	O
in	O
periods	O
of	O
deflation	O
.	O
</s>
<s>
On	O
27	O
August	O
2021	O
,	O
the	O
blockchain	B-Application
experienced	O
a	O
brief	O
fork	O
that	O
was	O
the	O
result	O
of	O
clients	O
running	O
different	O
incompatible	O
software	O
versions	O
.	O
</s>
<s>
Ethereum	B-Application
2.0	O
(	O
Eth2	O
)	O
was	O
a	O
set	O
of	O
three	O
or	O
more	O
upgrades	O
,	O
also	O
known	O
as	O
"	O
phases	O
"	O
,	O
meant	O
to	O
transition	O
the	O
network	O
's	O
consensus	B-Operating_System
mechanism	I-Operating_System
to	O
proof-of-stake	B-Protocol
,	O
and	O
to	O
scale	O
the	O
network	O
's	O
transaction	O
throughput	O
with	O
execution	O
sharding	B-General_Concept
and	O
an	O
improved	O
EVM	O
architecture	O
.	O
</s>
<s>
The	O
switch	O
from	O
proof-of-work	O
to	O
proof-of-stake	B-Protocol
has	O
cut	O
Ethereum	B-Application
's	O
energy	O
usage	O
by	O
99%	O
.	O
</s>
<s>
However	O
,	O
the	O
impact	O
this	O
has	O
on	O
global	O
energy	O
consumption	O
and	O
climate	O
change	O
may	O
be	O
limited	O
since	O
the	O
computers	O
previously	O
used	O
for	O
mining	O
ether	B-Application
may	O
be	O
used	O
to	O
mine	O
other	O
cryptocurrencies	O
that	O
are	O
energy-intensive	O
.	O
</s>
<s>
Ether	B-Application
(	O
ETH	O
)	O
is	O
the	O
cryptocurrency	O
generated	O
in	O
accordance	O
with	O
the	O
Ethereum	B-Application
protocol	O
as	O
a	O
reward	O
to	O
validators	O
in	O
a	O
proof-of-stake	B-Protocol
system	O
for	O
adding	O
blocks	O
to	O
the	O
blockchain	B-Application
.	O
</s>
<s>
Ether	B-Application
is	O
represented	O
in	O
the	O
state	O
as	O
an	O
unsigned	B-Algorithm
integer	O
associated	O
with	O
each	O
account	O
,	O
this	O
being	O
the	O
account	O
's	O
ETH	O
balance	O
denominated	O
in	O
wei	O
(	O
1018	O
wei	O
=	O
1	O
ether	B-Application
)	O
.	O
</s>
<s>
Additionally	O
,	O
ether	B-Application
is	O
the	O
only	O
currency	O
accepted	O
by	O
the	O
protocol	O
as	O
payment	O
for	O
the	O
transaction	O
fee	O
.	O
</s>
<s>
The	O
validator	O
reward	O
together	O
with	O
the	O
tips	O
provide	O
the	O
incentive	O
to	O
validators	O
to	O
keep	O
the	O
blockchain	B-Application
growing	O
(	O
i.e.	O
</s>
<s>
Ether	B-Application
may	O
be	O
"	O
sent	O
"	O
from	O
one	O
account	O
to	O
another	O
via	O
a	O
transaction	O
,	O
which	O
simply	O
entails	O
subtracting	O
the	O
amount	O
to	O
be	O
sent	O
from	O
the	O
sender	O
's	O
balance	O
and	O
adding	O
the	O
same	O
amount	O
to	O
the	O
recipient	O
's	O
balance	O
.	O
</s>
<s>
Ether	B-Application
is	O
often	O
erroneously	O
referred	O
to	O
as	O
"	O
Ethereum	B-Application
"	O
.	O
</s>
<s>
There	O
are	O
two	O
types	O
of	O
accounts	O
on	O
Ethereum	B-Application
:	O
user	O
accounts	O
(	O
also	O
known	O
as	O
externally-owned	O
accounts	O
)	O
and	O
contracts	O
.	O
</s>
<s>
Both	O
types	O
have	O
an	O
ETH	O
balance	O
,	O
may	O
send	O
ETH	O
to	O
any	O
account	O
,	O
may	O
call	O
any	O
public	O
function	O
of	O
a	O
contract	O
or	O
create	O
a	O
new	O
contract	O
,	O
and	O
are	O
identified	O
on	O
the	O
blockchain	B-Application
and	O
in	O
the	O
state	O
by	O
an	O
account	O
address	O
.	O
</s>
<s>
Contracts	O
are	O
the	O
only	O
type	O
of	O
account	O
that	O
has	O
associated	O
code	B-Application
(	O
a	O
set	O
of	O
functions	O
and	O
variable	O
declarations	O
)	O
and	O
contract	O
storage	B-General_Concept
(	O
the	O
values	O
of	O
the	O
variables	O
at	O
any	O
given	O
time	O
)	O
.	O
</s>
<s>
A	O
contract	O
function	O
may	O
take	O
arguments	O
and	O
may	O
have	O
return	B-Language
values	I-Language
.	O
</s>
<s>
In	O
addition	O
to	O
control	O
flow	O
statements	O
,	O
the	O
body	O
of	O
a	O
function	O
may	O
include	O
instructions	O
to	O
send	O
ETH	O
,	O
read	O
from	O
and	O
write	O
to	O
the	O
contract	O
's	O
storage	B-General_Concept
,	O
create	O
temporary	O
storage	B-General_Concept
(	O
memory	B-General_Concept
)	O
that	O
vanishes	O
at	O
the	O
end	O
of	O
the	O
function	O
,	O
perform	O
arithmetic	O
and	O
hashing	O
operations	O
,	O
call	O
the	O
contract	O
's	O
own	O
functions	O
or	O
public	O
functions	O
of	O
other	O
contracts	O
,	O
create	O
new	O
contracts	O
,	O
and	O
query	O
information	O
about	O
the	O
current	O
transaction	O
or	O
the	O
blockchain	B-Application
.	O
</s>
<s>
Ethereum	B-Application
addresses	O
are	O
composed	O
of	O
the	O
prefix	O
"	O
0x	O
"	O
(	O
a	O
common	O
identifier	O
for	O
hexadecimal	O
)	O
concatenated	O
with	O
the	O
rightmost	O
20	O
bytes	O
of	O
the	O
Keccak-256	B-Algorithm
hash	O
of	O
the	O
ECDSA	O
public	B-Application
key	I-Application
(	O
the	O
curve	O
used	O
is	O
the	O
so-called	O
secp256k1	O
)	O
.	O
</s>
<s>
The	O
Ethereum	B-Application
Virtual	O
Machine	O
(	O
EVM	O
)	O
is	O
the	O
runtime	B-Library
environment	O
for	O
transaction	O
execution	O
in	O
Ethereum	B-Application
.	O
</s>
<s>
It	O
includes	O
,	O
among	O
other	O
things	O
,	O
a	O
stack	B-Application
,	O
memory	B-General_Concept
,	O
gas	O
balance	O
,	O
program	B-General_Concept
counter	I-General_Concept
,	O
and	O
the	O
state	O
(	O
including	O
contract	O
code	B-Application
)	O
.	O
</s>
<s>
The	O
EVM	O
is	O
stack-based	O
,	O
in	O
that	O
most	O
instructions	O
pop	O
operands	O
from	O
the	O
stack	B-Application
and	O
push	O
the	O
result	O
to	O
the	O
stack	B-Application
.	O
</s>
<s>
The	O
EVM	O
is	O
designed	O
to	O
be	O
deterministic	O
on	O
a	O
wide	O
variety	O
of	O
hardware	O
and	O
operating	B-General_Concept
systems	I-General_Concept
,	O
so	O
that	O
given	O
a	O
pre-transaction	O
state	O
and	O
a	O
transaction	O
,	O
each	O
node	O
produces	O
the	O
same	O
post-transaction	O
state	O
,	O
thereby	O
enabling	O
network	O
consensus	O
.	O
</s>
<s>
The	O
formal	O
definition	O
of	O
the	O
EVM	O
is	O
specified	O
in	O
the	O
Ethereum	B-Application
Yellow	O
Paper	O
.	O
</s>
<s>
EVMs	O
have	O
been	O
implemented	O
in	O
C++	B-Language
,	O
C#	B-Application
,	O
Go	B-Application
,	O
Haskell	B-Language
,	O
Java	B-Language
,	O
JavaScript	B-Language
,	O
Python	B-Language
,	O
Ruby	B-Language
,	O
Rust	B-Application
,	O
Elixir	B-Language
,	O
Erlang	B-Operating_System
,	O
and	O
soon	O
WebAssembly	B-Language
.	O
</s>
<s>
Gas	O
is	O
a	O
unit	O
of	O
account	O
within	O
the	O
EVM	O
used	O
in	O
the	O
calculation	O
of	O
the	O
transaction	O
fee	O
,	O
which	O
is	O
the	O
amount	O
of	O
ETH	O
a	O
transaction	O
's	O
sender	O
must	O
pay	O
to	O
the	O
network	O
to	O
have	O
the	O
transaction	O
included	O
in	O
the	O
blockchain	B-Application
.	O
</s>
<s>
Each	O
type	O
of	O
operation	O
which	O
may	O
be	O
performed	O
by	O
the	O
EVM	O
is	O
hardcoded	B-Application
with	O
a	O
certain	O
gas	O
cost	O
,	O
which	O
is	O
intended	O
to	O
be	O
roughly	O
proportional	O
to	O
the	O
monetary	O
value	O
of	O
the	O
resources	O
(	O
e.g.	O
</s>
<s>
computation	O
and	O
storage	B-General_Concept
)	O
a	O
node	O
must	O
expend	O
or	O
dedicate	O
to	O
perform	O
that	O
operation	O
.	O
</s>
<s>
A	O
transaction	O
may	O
only	O
be	O
included	O
in	O
the	O
blockchain	B-Application
at	O
a	O
block	O
slot	O
that	O
has	O
a	O
base	O
gas	O
price	O
less	O
than	O
or	O
equal	O
to	O
the	O
transaction	O
's	O
gas	O
price	O
.	O
</s>
<s>
The	O
portion	O
of	O
the	O
gas	O
price	O
that	O
is	O
in	O
excess	O
of	O
the	O
base	O
gas	O
price	O
is	O
known	O
as	O
the	O
tip	O
and	O
goes	O
to	O
the	O
block	O
proposer	O
;	O
the	O
higher	O
the	O
tip	O
,	O
the	O
more	O
incentive	O
a	O
block	O
proposer	O
has	O
to	O
include	O
the	O
transaction	O
in	O
their	O
block	O
,	O
and	O
thus	O
the	O
quicker	O
the	O
transaction	O
will	O
be	O
included	O
in	O
the	O
blockchain	B-Application
.	O
</s>
<s>
In	O
user	B-Application
interfaces	I-Application
,	O
gas	O
prices	O
are	O
typically	O
denominated	O
in	O
gigawei	O
(	O
Gwei	O
)	O
,	O
a	O
subunit	O
of	O
ETH	O
equal	O
to	O
10−9	O
ETH	O
.	O
</s>
<s>
The	O
EVM	O
's	O
instruction	B-General_Concept
set	I-General_Concept
is	O
Turing-complete	B-Algorithm
.	O
</s>
<s>
Popular	O
uses	O
of	O
Ethereum	B-Application
have	O
included	O
the	O
creation	O
of	O
fungible	O
(	O
ERC-20	O
)	O
and	O
non-fungible	O
(	O
ERC-721	O
)	O
tokens	O
with	O
a	O
variety	O
of	O
properties	O
,	O
crowdfunding	O
(	O
e.g.	O
</s>
<s>
initial	B-Application
coin	I-Application
offerings	I-Application
)	O
,	O
decentralized	B-Protocol
finance	I-Protocol
,	O
decentralized	O
exchanges	O
,	O
decentralized	B-Operating_System
autonomous	I-Operating_System
organizations	I-Operating_System
(	O
DAOs	O
)	O
,	O
games	O
,	O
prediction	O
markets	O
,	O
and	O
gambling	O
.	O
</s>
<s>
Ethereum	B-Application
's	O
smart	B-Application
contracts	I-Application
are	O
written	O
in	O
high-level	B-Language
programming	I-Language
languages	I-Language
and	O
then	O
compiled	B-Language
down	O
to	O
EVM	O
bytecode	O
and	O
deployed	O
to	O
the	O
Ethereum	B-Application
blockchain	B-Application
.	O
</s>
<s>
They	O
can	O
be	O
written	O
in	O
Solidity	B-Protocol
(	O
a	O
language	O
library	O
with	O
similarities	O
to	O
C	B-Language
and	O
JavaScript	B-Language
)	O
,	O
Serpent	O
(	O
similar	O
to	O
Python	B-Language
,	O
but	O
deprecated	O
)	O
,	O
Yul	O
(	O
an	O
intermediate	O
language	O
that	O
can	O
compile	B-Language
to	O
various	O
different	O
backends	O
—	O
EVM	O
1.0	O
,	O
EVM	O
1.5	O
,	O
and	O
eWASM	O
are	O
planned	O
)	O
,	O
LLL	O
(	O
a	O
low-level	B-Language
Lisp-like	O
language	O
)	O
,	O
and	O
Mutan	O
(	O
Go-based	O
,	O
but	O
deprecated	O
)	O
.	O
</s>
<s>
There	O
was	O
also	O
a	O
research-oriented	O
language	O
under	O
development	O
called	O
Vyper	O
(	O
a	O
strongly-typed	O
Python-derived	O
decidable	O
language	O
)	O
.	O
</s>
<s>
Source	O
code	B-Application
and	O
compiler	B-Language
information	O
are	O
usually	O
published	O
along	O
with	O
the	O
launch	O
of	O
the	O
contract	O
so	O
that	O
users	O
can	O
see	O
the	O
code	B-Application
and	O
verify	O
that	O
it	O
compiles	B-Language
to	O
the	O
bytecode	O
that	O
is	O
on-chain	O
.	O
</s>
<s>
One	O
issue	O
related	O
to	O
using	O
smart	B-Application
contracts	I-Application
on	O
a	O
public	O
blockchain	B-Application
is	O
that	O
bugs	O
,	O
including	O
security	O
holes	O
,	O
are	O
visible	O
to	O
all	O
but	O
cannot	O
be	O
fixed	O
quickly	O
.	O
</s>
<s>
One	O
example	O
of	O
this	O
is	O
the	O
2016	O
attack	O
on	O
The	B-Protocol
DAO	I-Protocol
,	O
which	O
could	O
not	O
be	O
quickly	O
stopped	O
or	O
reversed	O
.	O
</s>
<s>
The	O
ERC-20	O
(	O
Ethereum	B-Application
Request-for-Comments	O
#20	O
)	O
Token	O
Standard	O
allows	O
for	O
fungible	O
tokens	O
on	O
the	O
Ethereum	B-Application
blockchain	B-Application
.	O
</s>
<s>
The	O
standard	O
,	O
proposed	O
by	O
Fabian	O
Vogelsteller	O
in	O
November	O
2015	O
,	O
implements	O
an	O
API	B-General_Concept
for	O
tokens	O
within	O
smart	B-Application
contracts	I-Application
.	O
</s>
<s>
Smart	B-Application
contracts	I-Application
that	O
correctly	O
implement	O
ERC-20	O
processes	O
are	O
called	O
ERC-20	O
Token	O
Contracts	O
,	O
and	O
they	O
keep	O
track	O
of	O
created	O
tokens	O
on	O
Ethereum	B-Application
.	O
</s>
<s>
Numerous	O
cryptocurrencies	O
have	O
launched	O
as	O
ERC-20	O
tokens	O
and	O
have	O
been	O
distributed	O
through	O
initial	B-Application
coin	I-Application
offerings	I-Application
.	O
</s>
<s>
Ethereum	B-Application
also	O
allows	O
for	O
the	O
creation	O
of	O
unique	O
and	O
indivisible	O
tokens	O
,	O
called	O
non-fungible	O
tokens	O
(	O
NFTs	O
)	O
.	O
</s>
<s>
Decentralized	B-Protocol
finance	I-Protocol
(	O
DeFi	B-Protocol
)	O
offers	O
traditional	O
financial	O
instruments	O
in	O
a	O
decentralized	O
architecture	O
,	O
outside	O
of	O
companies	O
 '	O
and	O
governments	O
 '	O
control	O
,	O
such	O
as	O
money	O
market	O
funds	O
which	O
let	O
users	O
earn	O
interest	O
.	O
</s>
<s>
DeFi	B-Protocol
applications	O
are	O
typically	O
accessed	O
through	O
a	O
Web3-enabled	O
browser	O
extension	O
or	O
application	O
,	O
such	O
as	O
MetaMask	B-Protocol
,	O
which	O
allows	O
users	O
to	O
directly	O
interact	O
with	O
the	O
Ethereum	B-Application
blockchain	B-Application
through	O
a	O
website	O
.	O
</s>
<s>
Many	O
of	O
these	O
DApps	B-Application
can	O
connect	O
and	O
work	O
together	O
to	O
create	O
complex	O
financial	O
services	O
.	O
</s>
<s>
Examples	O
of	O
DeFi	B-Protocol
platforms	O
include	O
MakerDAO	B-Protocol
and	O
Compound	O
.	O
</s>
<s>
Uniswap	B-Protocol
,	O
a	O
decentralized	O
exchange	O
for	O
tokens	O
on	O
Ethereum	B-Application
grew	O
from	O
in	O
liquidity	O
to	O
in	O
2020	O
.	O
</s>
<s>
As	O
of	O
October	O
2020	O
,	O
over	O
was	O
invested	O
in	O
various	O
DeFi	B-Protocol
protocols	O
.	O
</s>
<s>
Additionally	O
,	O
through	O
a	O
process	O
called	O
"	O
wrapping	O
"	O
,	O
certain	O
DeFi	B-Protocol
protocols	O
allow	O
synthetic	O
versions	O
of	O
various	O
assets	O
(	O
such	O
as	O
bitcoin	B-Protocol
,	O
gold	O
,	O
and	O
oil	O
)	O
to	O
be	O
tradeable	O
on	O
Ethereum	B-Application
and	O
also	O
compatible	O
with	O
all	O
of	O
Ethereum	B-Application
's	O
major	O
wallets	O
and	O
applications	O
.	O
</s>
<s>
Ethereum-based	O
software	O
and	O
networks	O
,	O
independent	O
from	O
the	O
public	O
Ethereum	B-Application
chain	O
,	O
are	O
being	O
tested	O
by	O
enterprise	B-Application
software	I-Application
companies	O
.	O
</s>
<s>
Barclays	O
,	O
UBS	O
,	O
Credit	O
Suisse	O
,	O
Amazon	B-Application
,	O
Visa	O
,	O
and	O
other	O
companies	O
are	O
also	O
experimenting	O
with	O
Ethereum	B-Application
.	O
</s>
<s>
Ethereum-based	O
permissioned	O
blockchain	B-Application
variants	O
are	O
used	O
and	O
being	O
investigated	O
for	O
various	O
projects	O
:	O
</s>
<s>
In	O
2017	O
,	O
JPMorgan	O
Chase	O
proposed	O
developing	O
JPM	O
Coin	O
on	O
a	O
permissioned-variant	O
of	O
Ethereum	B-Application
blockchain	B-Application
dubbed	O
"	O
Quorum	O
"	O
.	O
</s>
<s>
The	O
downside	O
is	O
that	O
performance	O
issues	O
arise	O
because	O
every	O
node	O
calculates	O
all	O
the	O
smart	B-Application
contracts	I-Application
in	O
real-time	O
.	O
</s>
<s>
,	O
the	O
Ethereum	B-Application
protocol	O
could	O
process	O
about	O
25	O
transactions	O
per	O
second	O
;	O
this	O
did	O
not	O
change	O
after	O
the	O
proof-of-stake	B-Protocol
implementation	O
.	O
</s>
<s>
This	O
has	O
led	O
some	O
to	O
question	O
the	O
scalability	O
of	O
Ethereum	B-Application
.	O
</s>
<s>
Ethereum	B-Application
engineers	O
have	O
been	O
working	O
on	O
sharding	B-General_Concept
the	O
calculations	O
,	O
and	O
the	O
next	O
step	O
(	O
Ethereum	B-Application
2	O
)	O
was	O
presented	O
at	O
Ethereum	B-Application
's	O
Devcon	O
3	O
in	O
November	O
2017	O
.	O
</s>
<s>
Ethereum	B-Application
's	O
blockchain	B-Application
uses	O
Merkle	B-Algorithm
trees	I-Algorithm
for	O
security	O
reasons	O
,	O
to	O
improve	O
scalability	O
,	O
and	O
to	O
optimize	O
transaction	O
hashing	O
.	O
</s>
<s>
As	O
with	O
any	O
Merkle	B-Algorithm
tree	I-Algorithm
implementation	O
,	O
this	O
allows	O
for	O
storage	B-General_Concept
savings	O
,	O
set	O
membership	O
proofs	O
(	O
called	O
"	O
Merkle	O
proofs	O
"	O
)	O
,	O
and	O
light	O
client	O
synchronization	O
.	O
</s>
<s>
The	O
network	O
has	O
faced	O
congestion	O
problems	O
,	O
such	O
as	O
in	O
2017	O
in	O
relation	O
to	O
CryptoKitties	B-Protocol
.	O
</s>
<s>
In	O
the	O
United	O
States	O
,	O
the	O
proposed	O
Digital	O
Commodities	O
Consumer	O
Protection	O
Act	O
would	O
treat	O
Ethereum	B-Application
and	O
other	O
cryptocurrencies	O
as	O
commodities	O
,	O
which	O
could	O
then	O
be	O
regulated	O
by	O
the	O
Commodity	O
Futures	O
Trading	O
Commission	O
(	O
CFTC	O
)	O
.	O
</s>
