<s>
A	O
product	B-Application
key	I-Application
,	O
also	O
known	O
as	O
a	O
software	B-Application
key	I-Application
,	O
serial	B-Application
key	I-Application
or	O
activation	O
key	O
,	O
is	O
a	O
specific	O
software-based	O
key	O
for	O
a	O
computer	B-Application
program	I-Application
.	O
</s>
<s>
Product	B-Application
keys	I-Application
consist	O
of	O
a	O
series	O
of	O
numbers	O
and/or	O
letters	O
.	O
</s>
<s>
Standard	O
key	O
generation	O
,	O
where	O
product	B-Application
keys	I-Application
are	O
generated	O
mathematically	O
,	O
is	O
not	O
completely	O
effective	O
in	O
stopping	O
copyright	O
infringement	O
of	O
software	O
,	O
as	O
these	O
keys	O
can	O
be	O
distributed	O
.	O
</s>
<s>
In	O
addition	O
,	O
with	O
improved	O
communication	O
from	O
the	O
rise	O
of	O
the	O
Internet	O
,	O
more	O
sophisticated	O
attacks	O
on	O
keys	O
such	O
as	O
cracks	B-Application
(	O
removing	O
the	O
need	O
for	O
a	O
key	O
)	O
and	O
product	B-Application
key	I-Application
generators	O
have	O
become	O
common	O
.	O
</s>
<s>
Because	O
of	O
this	O
,	O
software	O
publishers	O
use	O
additional	O
product	B-License
activation	I-License
methods	O
to	O
verify	O
that	O
keys	O
are	O
both	O
valid	O
and	O
uncompromised	O
.	O
</s>
<s>
One	O
method	O
assigns	O
a	O
product	B-Application
key	I-Application
based	O
on	O
a	O
unique	O
feature	O
of	O
the	O
purchaser	O
's	O
computer	O
hardware	O
,	O
which	O
cannot	O
be	O
as	O
easily	O
duplicated	O
since	O
it	O
depends	O
on	O
the	O
user	O
's	O
hardware	O
.	O
</s>
<s>
Another	O
method	O
involves	O
requiring	O
one-time	O
or	O
periodical	O
validation	O
of	O
the	O
product	B-Application
key	I-Application
with	O
an	O
internet	O
server	O
(	O
for	O
games	O
with	O
an	O
online	O
component	O
,	O
this	O
is	O
done	O
whenever	O
the	O
user	O
signs	O
in	O
)	O
.	O
</s>
<s>
Windows	O
95	O
retail	O
product	B-Application
keys	I-Application
take	O
the	O
form	O
XXX-XXXXXXX	O
.	O
</s>
<s>
If	O
all	O
checks	O
pass	O
,	O
the	O
product	B-Application
key	I-Application
is	O
valid	O
.	O
</s>
<s>
Some	O
of	O
the	O
most	O
effective	O
product	B-Application
key	I-Application
protections	O
are	O
controversial	O
due	O
to	O
inconvenience	O
,	O
strict	O
enforcement	O
,	O
harsh	O
penalties	O
and	O
,	O
in	O
some	O
cases	O
,	O
false	O
positives	O
.	O
</s>
<s>
Some	O
product	B-Application
keys	I-Application
use	O
uncompromising	O
digital	O
procedures	O
to	O
enforce	O
the	O
license	O
agreement	O
.	O
</s>
<s>
Product	B-Application
keys	I-Application
are	O
somewhat	O
inconvenient	O
for	O
end	O
users	O
.	O
</s>
<s>
Loss	O
of	O
a	O
product	B-Application
key	I-Application
usually	O
means	O
the	O
software	O
is	O
useless	O
once	O
uninstalled	O
,	O
unless	O
,	O
prior	O
to	O
uninstallation	O
,	O
a	O
key	O
recovery	O
application	O
is	O
used	O
(	O
although	O
not	O
all	O
programs	O
support	O
this	O
)	O
.	O
</s>
<s>
Product	B-Application
keys	I-Application
also	O
present	O
new	O
ways	O
for	O
distribution	O
to	O
go	O
wrong	O
.	O
</s>
<s>
For	O
example	O
,	O
all	O
copies	O
of	O
Splinter	B-Application
Cell	I-Application
:	I-Application
Pandora	I-Application
Tomorrow	I-Application
originally	O
shipped	O
to	O
Australia	O
without	O
product	B-Application
keys	I-Application
.	O
</s>
<s>
It	O
is	O
common	O
for	O
an	O
online	O
system	O
to	O
immediately	O
blacklist	O
an	O
account	O
caught	O
running	O
cracks	B-Application
or	O
,	O
in	O
some	O
cases	O
,	O
cheats	O
.	O
</s>
<s>
Bans	O
are	O
enforced	O
by	O
servers	O
immediately	O
upon	O
detection	O
of	O
cracks	B-Application
or	O
cheats	O
,	O
usually	O
without	O
human	O
intervention	O
.	O
</s>
<s>
In	O
large	O
cases	O
of	O
false	O
positives	O
,	O
they	O
are	O
sometimes	O
corrected	O
(	O
as	O
happened	O
in	O
World	B-Protocol
of	I-Protocol
Warcraft	I-Protocol
.	O
)	O
</s>
<s>
A	O
common	O
cause	O
of	O
false	O
positives	O
(	O
as	O
with	O
the	B-Protocol
World	I-Protocol
of	I-Protocol
Warcraft	I-Protocol
case	O
above	O
)	O
is	O
users	O
of	O
unsupported	O
platforms	O
.	O
</s>
<s>
For	O
example	O
,	O
users	O
of	O
Linux	B-Application
can	O
run	O
Windows	O
applications	O
through	O
compatibility	O
layers	O
such	O
as	O
Wine	B-Application
and	O
Cedega	B-General_Concept
.	O
</s>
<s>
This	O
software	O
combination	O
sometimes	O
triggers	O
the	O
game	O
's	O
server	O
anti-cheating	O
software	O
,	O
resulting	O
in	O
a	O
ban	O
due	O
to	O
Wine	B-Application
or	O
Cedega	B-General_Concept
being	O
a	O
Windows	O
API	O
compatibility	O
layer	O
for	O
Linux	B-Application
,	O
so	O
it	O
is	O
considered	O
third-party	O
(	O
cheating	O
)	O
software	O
by	O
the	O
game	O
's	O
server	O
.	O
</s>
