<s>
In	O
blockchain	B-Application
technology	I-Application
,	O
a	O
testnet	B-Protocol
is	O
an	O
instance	O
of	O
a	O
blockchain	B-Application
powered	O
by	O
the	O
same	O
or	O
a	O
newer	O
version	O
of	O
the	O
underlying	O
software	O
,	O
to	O
be	O
used	O
for	O
testing	O
and	O
experimentation	O
without	O
risk	O
to	O
real	O
funds	O
or	O
the	O
main	O
chain	O
.	O
</s>
<s>
Testnet	B-Protocol
coins	O
are	O
separate	O
and	O
distinct	O
from	O
the	O
official	O
(	O
mainnet	O
)	O
coins	O
,	O
do	O
n't	O
have	O
value	O
,	O
and	O
can	O
be	O
obtained	O
freely	O
from	O
faucets	O
.	O
</s>
<s>
Testnets	B-Protocol
allow	O
for	O
the	O
development	O
of	O
blockchain	B-Application
applications	O
without	O
the	O
risk	O
of	O
losing	O
funds	O
.	O
</s>
<s>
A	O
bug	O
was	O
discovered	O
in	O
the	O
Bitcoin	B-Protocol
Core	I-Protocol
software	O
that	O
gave	O
miners	O
the	O
ability	O
to	O
take	O
down	O
essential	O
parts	O
of	O
the	O
Bitcoin	B-Protocol
infrastructure	O
(	O
nodes	O
)	O
by	O
sending	O
a	O
'	O
bad	O
 '	O
block	O
to	O
the	O
blockchain	B-Application
.	O
</s>
