<s>
Immunet	B-Application
is	O
a	O
free	O
,	O
cloud-based	B-Architecture
,	O
community-driven	O
antivirus	B-Application
application	O
,	O
using	O
the	O
ClamAV	B-Application
and	O
its	O
own	O
engine	O
.	O
</s>
<s>
The	O
software	O
is	O
complementary	O
with	O
existing	O
antivirus	B-Application
software	I-Application
.	O
</s>
<s>
In	O
January	O
2011	O
Immunet	B-Application
was	O
acquired	O
by	O
Sourcefire	O
.	O
</s>
<s>
Virus	O
signature	B-General_Concept
files	I-General_Concept
are	O
stored	O
in	B-Architecture
the	I-Architecture
cloud	I-Architecture
,	O
not	O
on	O
individual	O
computers	O
,	O
so	O
signature	O
downloads	O
are	O
not	O
required	O
.	O
</s>
<s>
Once	O
a	O
virus	O
is	O
detected	O
and	O
blocked	O
for	O
one	O
user	O
,	O
all	O
other	O
Immunet	B-Application
users	O
receive	O
the	O
same	O
protection	O
almost	O
instantly	O
.	O
</s>
<s>
Immunet	B-Application
was	O
previously	O
provided	O
by	O
Sourcefire	O
in	O
two	O
editions	O
,	O
Free	O
(	O
for	O
personal	O
use	O
)	O
,	O
and	O
Plus	O
(	O
for	O
commercial	O
use	O
)	O
.	O
</s>
<s>
At	O
version	O
3.0	O
,	O
Immunet	B-Application
Free	O
offers	O
protection	O
based	O
upon	O
the	O
virus	O
definitions	O
in	B-Architecture
the	I-Architecture
cloud	I-Architecture
,	O
and	O
an	O
option	O
to	O
include	O
the	O
ClamAV	B-Application
off-line	O
virus	O
definitions	O
for	O
use	O
when	O
not	O
connected	O
to	O
the	O
Internet	O
.	O
</s>
<s>
Immunet	B-Application
advises	O
that	O
the	O
free	O
version	O
be	O
used	O
alongside	O
another	O
antivirus	B-Application
program	I-Application
,	O
and	O
supports	O
several	O
particular	O
such	O
programs	O
in	O
the	O
sense	O
that	O
they	O
co-install	O
properly	O
and	O
work	O
in	O
tandem	O
during	O
normal	O
operations	O
without	O
any	O
obvious	O
interference	O
or	O
resource	O
drag	O
.	O
</s>
<s>
This	O
is	O
a	O
significant	O
difference	O
between	O
Immunet	B-Application
and	O
other	O
contemporary	O
antivirus	B-Application
products	O
.	O
</s>
<s>
Immunet	B-Application
's	O
virus	O
definitions	O
are	O
stored	O
on	O
servers	O
available	O
over	O
the	O
Internet	O
,	O
requiring	O
less	O
memory	O
and	O
system	O
resource	O
than	O
antivirus	B-Application
programs	O
that	O
reside	O
on	O
the	O
user	O
's	O
computer	O
.	O
</s>
<s>
In	O
Windows	O
8.1	O
and	O
10	O
,	O
older	O
versions	O
of	O
Immunet	B-Application
such	O
as	O
3.x	O
only	O
satisfies	O
Virus	B-Application
protection	I-Application
but	O
not	O
Spyware	O
and	O
unwanted	O
software	O
protection	O
in	O
Action	O
Center	O
alerts	O
on	O
toolbar	O
unlike	O
other	O
commercial	O
antiviruses	O
which	O
satisfy	O
both	O
.	O
</s>
