<s>
Bitcoin	B-Protocol
Gold	I-Protocol
(	O
BTG	O
)	O
is	O
a	O
cryptocurrency	O
.	O
</s>
<s>
It	O
is	O
a	O
hard	O
fork	O
of	O
Bitcoin	B-Protocol
,	O
the	O
open	B-Application
source	I-Application
cryptocurrency	O
.	O
</s>
<s>
It	O
is	O
an	O
open	B-Application
source	I-Application
,	O
decentralized	O
digital	O
currency	O
without	O
a	O
central	O
bank	O
or	O
intermediary	O
that	O
can	O
be	O
sent	O
from	O
user	O
to	O
user	O
on	O
the	O
peer-to-peer	O
Bitcoin	B-Protocol
Gold	I-Protocol
network	O
.	O
</s>
<s>
The	O
stated	O
purpose	O
of	O
the	O
hard	O
fork	O
is	O
to	O
change	O
the	O
proof	O
of	O
work	O
algorithm	O
so	O
that	O
ASICs	O
(	O
Application-Specific	O
Integrated	O
Circuits	O
)	O
which	O
are	O
used	O
to	O
mine	O
Bitcoin	B-Protocol
cannot	O
be	O
used	O
to	O
mine	O
the	O
Bitcoin	B-Protocol
Gold	I-Protocol
blockchain	B-Application
in	O
the	O
hopes	O
that	O
enabling	O
mining	O
on	O
commonly	O
available	O
graphics	O
cards	O
will	O
democratize	O
and	O
decentralize	O
the	O
mining	O
and	O
distribution	O
of	O
the	O
cryptocurrency	O
.	O
</s>
<s>
Bitcoin	B-Protocol
Gold	I-Protocol
hard	O
forked	O
from	O
the	O
Bitcoin	B-Protocol
blockchain	B-Application
on	O
October	O
24	O
,	O
2017	O
,	O
at	O
block	B-Application
height	I-Application
491407	O
.	O
</s>
<s>
In	O
July	O
2018	O
,	O
Bitcoin	B-Protocol
Gold	I-Protocol
implemented	O
a	O
new	O
mining	O
algorithm	O
.	O
</s>
<s>
The	O
actual	O
algorithm	O
that	O
was	O
developed	O
by	O
Zcash	B-Protocol
(	O
now	O
,	O
Electric	O
Coin	O
Company	O
)	O
was	O
based	O
on	O
parameter	O
set	O
<200,9>	O
.	O
</s>
<s>
Bitcoin	B-Protocol
Gold	I-Protocol
has	O
modified	O
this	O
algorithm	O
and	O
is	O
now	O
adopting	O
parameter	O
set	O
<144,5>	O
.	O
</s>
<s>
This	O
new	O
algorithm	O
is	O
called	O
Equihash-BTG	O
.	O
</s>
<s>
The	O
new	O
algorithm	O
requires	O
more	O
memory	O
than	O
the	O
one	O
that	O
was	O
originally	O
developed	O
by	O
Zcash	B-Protocol
.	O
</s>
<s>
In	O
May	O
2018	O
,	O
Bitcoin	B-Protocol
Gold	I-Protocol
was	O
hit	O
by	O
a	O
51%	B-Operating_System
hashing	I-Operating_System
attack	I-Operating_System
by	O
an	O
unknown	O
actor	O
.	O
</s>
<s>
This	O
type	O
of	O
attack	O
makes	O
it	O
possible	O
to	O
manipulate	O
the	O
blockchain	B-Application
ledger	O
on	O
which	O
transactions	O
are	O
recorded	O
,	O
and	O
to	O
spend	O
the	O
same	O
digital	O
coins	O
more	O
than	O
once	O
.	O
</s>
<s>
Bitcoin	B-Protocol
Gold	I-Protocol
was	O
later	O
delisted	O
from	O
Bittrex	O
,	O
after	O
the	O
team	O
refused	O
to	O
help	O
pay	O
some	O
damages	O
.	O
</s>
<s>
Bitcoin	B-Protocol
Gold	I-Protocol
suffered	O
from	O
51%	O
attacks	O
again	O
in	O
January	O
2020	O
.	O
</s>
