<s>
Prime95	O
,	O
also	O
distributed	O
as	O
the	O
command-line	O
utility	O
mprime	B-Application
for	O
FreeBSD	B-Operating_System
and	O
Linux	B-Application
,	O
is	O
a	O
freeware	B-License
application	B-Application
written	O
by	O
George	O
Woltman	O
.	O
</s>
<s>
It	O
is	O
the	O
official	O
client	O
of	O
the	O
Great	O
Internet	O
Mersenne	O
Prime	O
Search	O
(	O
GIMPS	O
)	O
,	O
a	O
volunteer	B-Operating_System
computing	I-Operating_System
project	O
dedicated	O
to	O
searching	O
for	O
Mersenne	O
primes	O
.	O
</s>
<s>
It	O
is	O
also	O
used	O
in	O
overclocking	B-Application
to	O
test	O
for	O
system	O
stability	O
.	O
</s>
<s>
Although	O
most	O
of	O
its	O
source	B-License
code	I-License
is	I-License
available	I-License
,	O
Prime95	O
is	O
not	O
free	B-License
and	I-License
open-source	I-License
software	I-License
because	O
its	O
end-user	O
license	O
agreement	O
states	O
that	O
if	O
the	O
software	O
is	O
used	O
to	O
find	O
a	O
prime	O
qualifying	O
for	O
a	O
bounty	O
offered	O
by	O
the	O
Electronic	O
Frontier	O
Foundation	O
,	O
then	O
that	O
bounty	O
will	O
be	O
claimed	O
and	O
distributed	O
by	O
GIMPS	O
.	O
</s>
<s>
Prime95	O
tests	O
numbers	O
for	O
primality	O
using	O
the	O
Fermat	B-Algorithm
primality	I-Algorithm
test	I-Algorithm
(	O
referred	O
to	O
internally	O
as	O
PRP	O
,	O
or	O
"	O
probable	O
prime	O
"	O
)	O
.	O
</s>
<s>
For	O
much	O
of	O
its	O
history	O
,	O
it	O
used	O
the	O
Lucas	B-Algorithm
–	I-Algorithm
Lehmer	I-Algorithm
primality	I-Algorithm
test	I-Algorithm
,	O
but	O
the	O
availability	O
of	O
Lucas	O
–	O
Lehmer	O
assignments	O
was	O
deprecated	O
in	O
April	O
2021	O
to	O
increase	O
search	O
throughput	O
.	O
</s>
<s>
Specifically	O
,	O
to	O
guard	O
against	O
faulty	O
results	O
,	O
every	O
Lucas	B-Algorithm
–	I-Algorithm
Lehmer	I-Algorithm
test	I-Algorithm
had	O
to	O
be	O
performed	O
twice	O
in	O
its	O
entirety	O
,	O
while	O
Fermat	B-Algorithm
tests	I-Algorithm
can	O
be	O
verified	O
in	O
a	O
small	O
fraction	O
of	O
their	O
original	O
run	O
time	O
using	O
a	O
proof	O
generated	O
during	O
the	O
test	O
by	O
Prime95	O
.	O
</s>
<s>
Current	O
versions	O
of	O
Prime95	O
remain	O
capable	O
of	O
Lucas	O
–	O
Lehmer	O
testing	O
for	O
the	O
purpose	O
of	O
double-checking	O
existing	O
Lucas	O
–	O
Lehmer	O
results	O
,	O
and	O
for	O
fully	O
verifying	O
"	O
probably	O
prime	O
"	O
Fermat	B-Algorithm
test	I-Algorithm
results	O
(	O
which	O
,	O
unlike	O
"	O
prime	O
"	O
Lucas	O
–	O
Lehmer	O
results	O
,	O
are	O
not	O
conclusive	O
)	O
.	O
</s>
<s>
To	O
reduce	O
the	O
number	O
of	O
full-length	O
primality	O
tests	O
needed	O
,	O
Prime95	O
also	O
implements	O
other	O
,	O
computationally	O
simpler	O
tests	O
designed	O
to	O
filter	O
out	O
unviable	O
candidates	O
;	O
as	O
of	O
2021	O
,	O
this	O
mainly	O
comprises	O
Pollard	B-Algorithm
's	I-Algorithm
p	I-Algorithm
–	I-Algorithm
1	I-Algorithm
algorithm	I-Algorithm
.	O
</s>
<s>
The	O
elliptic-curve	B-Algorithm
factorization	I-Algorithm
method	I-Algorithm
and	O
Williams	B-Algorithm
's	I-Algorithm
p	I-Algorithm
+	I-Algorithm
1	I-Algorithm
algorithm	I-Algorithm
are	O
implemented	O
,	O
but	O
are	O
considered	O
not	O
useful	O
at	O
modern	O
GIMPS	O
testing	O
levels	O
,	O
and	O
mostly	O
used	O
in	O
attempts	O
to	O
factor	O
much	O
smaller	O
Mersenne	O
numbers	O
that	O
have	O
already	O
undergone	O
primality	O
testing	O
.	O
</s>
<s>
Prime95	O
implements	O
trial	B-Algorithm
division	I-Algorithm
,	O
but	O
because	O
this	O
type	O
of	O
work	O
can	O
be	O
executed	O
using	O
single-precision	O
arithmetic	O
(	O
as	O
opposed	O
to	O
the	O
double-precision	O
arithmetic	O
required	O
by	O
other	O
GIMPS	O
work	O
types	O
)	O
,	O
almost	O
all	O
GIMPS	O
trial	B-Algorithm
division	I-Algorithm
is	O
done	O
by	O
third-party	O
clients	O
implementing	O
GPU	B-Architecture
computation	O
for	O
its	O
comparatively	O
much	O
greater	O
single-precision	O
throughput	O
.	O
</s>
<s>
To	O
maximize	O
search	O
throughput	O
,	O
most	O
of	O
Prime95	O
is	O
written	O
in	O
hand-tuned	O
assembly	B-Language
,	O
which	O
makes	O
its	O
system	O
resource	O
usage	O
much	O
greater	O
than	O
most	O
other	O
computer	O
programs	O
.	O
</s>
<s>
These	O
factors	O
make	O
it	O
a	O
commonly	O
used	O
tool	O
among	O
overclockers	B-Application
to	O
check	O
the	O
stability	O
of	O
a	O
particular	O
configuration	O
.	O
</s>
