<s>
7-Zip	B-Language
is	O
a	O
free	B-License
and	I-License
open-source	I-License
file	B-Application
archiver	I-Application
,	O
a	O
utility	O
used	O
to	O
place	O
groups	O
of	O
files	O
within	O
compressed	O
containers	O
known	O
as	O
"	O
archives	O
"	O
.	O
</s>
<s>
It	O
is	O
developed	O
by	O
Igor	B-Language
Pavlov	I-Language
and	O
was	O
first	O
released	O
in	O
1999	O
.	O
</s>
<s>
7-Zip	B-Language
has	O
its	O
own	O
archive	O
format	O
called	O
7z	O
,	O
but	O
can	O
read	O
and	O
write	O
several	O
others	O
.	O
</s>
<s>
The	O
program	O
can	O
be	O
used	O
from	O
a	O
Windows	O
graphical	B-Application
user	I-Application
interface	I-Application
that	O
also	O
features	O
shell	O
integration	O
,	O
from	O
a	O
Windows	O
command-line	B-Application
interface	I-Application
as	O
the	O
command	O
7za.exe	O
,	O
and	O
from	O
POSIX	O
systems	O
as	O
p7zip	B-Language
.	O
</s>
<s>
Most	O
of	O
the	O
7-Zip	B-Language
source	O
code	O
is	O
under	O
the	O
LGPL-2.1-or-later	B-Application
license	O
;	O
the	O
unRAR	B-Application
code	O
,	O
however	O
,	O
is	O
under	O
the	O
LGPL-2.1-or-later	B-Application
license	O
with	O
an	O
"	O
unRAR	B-Application
restriction	O
"	O
,	O
which	O
states	O
that	O
developers	O
are	O
not	O
permitted	O
to	O
use	O
the	O
code	O
to	O
reverse-engineer	O
the	O
RAR	O
compression	B-General_Concept
algorithm	I-General_Concept
.	O
</s>
<s>
Since	O
version	O
21.01	O
alpha	O
,	O
preliminary	O
Linux	B-Application
support	O
has	O
been	O
added	O
to	O
the	O
upstream	O
instead	O
of	O
the	O
p7zip	B-Language
project	O
.	O
</s>
<s>
By	O
default	O
,	O
7-Zip	B-Language
creates	O
7z-format	O
archives	O
with	O
a	O
.7z	O
file	O
extension	O
.	O
</s>
<s>
These	O
can	O
consist	O
of	O
pre-processors	O
,	O
compression	B-General_Concept
algorithms	I-General_Concept
,	O
and	O
encryption	O
filters	O
.	O
</s>
<s>
The	O
core	O
7z	O
compression	O
uses	O
a	O
variety	O
of	O
algorithms	O
,	O
the	O
most	O
common	O
of	O
which	O
are	O
bzip2	B-Application
,	O
PPMd	B-Algorithm
,	O
LZMA2	B-General_Concept
,	O
and	O
LZMA	B-General_Concept
.	O
</s>
<s>
Developed	O
by	O
Pavlov	O
,	O
LZMA	B-General_Concept
is	O
a	O
relatively	O
new	O
system	O
,	O
making	O
its	O
debut	O
as	O
part	O
of	O
the	O
7z	O
format	O
.	O
</s>
<s>
LZMA	B-General_Concept
uses	O
an	O
LZ-based	O
sliding	O
dictionary	O
of	O
up	O
to	O
3840	O
MB	O
in	O
size	O
,	O
backed	O
by	O
a	O
range	B-Algorithm
coder	I-Algorithm
.	O
</s>
<s>
The	O
native	O
7z	O
file	O
format	O
is	O
open	O
and	O
modular	B-Architecture
.	O
</s>
<s>
In	O
2011	O
,	O
TopTenReviews	O
found	O
that	O
the	O
7z	O
compression	O
was	O
at	O
least	O
17%	O
better	O
than	O
ZIP	B-General_Concept
,	O
and	O
7-Zip	B-Language
'	O
s	O
own	O
site	O
has	O
since	O
2002	O
reported	O
that	O
while	O
compression	O
ratio	O
results	O
are	O
very	O
dependent	O
upon	O
the	O
data	O
used	O
for	O
the	O
tests	O
,	O
"	O
Usually	O
,	O
7-Zip	B-Language
compresses	O
to	O
7z	O
format	O
30	O
–	O
70%	O
better	O
than	O
to	O
zip	B-General_Concept
format	O
,	O
and	O
7-Zip	B-Language
compresses	O
to	O
zip	B-General_Concept
format	O
2	O
–	O
10%	O
better	O
than	O
most	O
other	O
zip-compatible	O
programs.	O
"	O
</s>
<s>
7-Zip	B-Language
supports	O
a	O
number	O
of	O
other	O
compression	O
and	O
non-compression	O
archive	O
formats	O
(	O
both	O
for	O
packing	O
and	O
unpacking	O
)	O
,	O
including	O
ZIP	B-General_Concept
,	O
gzip	B-Application
,	O
bzip2	B-Application
,	O
xz	B-Language
,	O
tar	B-Application
,	O
and	O
WIM	O
.	O
</s>
<s>
The	O
utility	O
also	O
supports	O
unpacking	O
APM	B-Application
,	O
ar	B-Application
,	O
ARJ	B-Application
,	O
chm	B-Protocol
,	O
cpio	B-Application
,	O
deb	O
,	O
FLV	B-Operating_System
,	O
JAR	B-Language
,	O
LHA/LZH	B-Application
,	O
LZMA	B-General_Concept
,	O
MSLZ	O
,	O
Office	B-Operating_System
Open	I-Operating_System
XML	I-Operating_System
,	O
onepkg	O
,	O
RAR	O
,	O
RPM	B-Application
,	O
smzip	O
,	O
SWF	O
,	O
XAR	B-Application
,	O
and	O
Z	B-Device
archives	O
and	O
cramfs	B-Application
,	O
DMG	B-Operating_System
,	O
FAT	B-Application
,	O
HFS	B-Application
,	O
ISO	B-General_Concept
,	O
MBR	B-Device
,	O
NTFS	B-Application
,	O
SquashFS	B-Application
,	O
UDF	O
,	O
and	O
VHD	O
disk	B-Application
images	I-Application
.	O
</s>
<s>
7-Zip	B-Language
supports	O
the	O
ZIPX	B-General_Concept
format	O
for	O
unpacking	O
only	O
.	O
</s>
<s>
7-Zip	B-Language
can	O
open	O
some	O
MSI	B-Application
files	O
,	O
allowing	O
access	O
to	O
the	O
meta-files	O
within	O
along	O
with	O
the	O
main	O
contents	O
.	O
</s>
<s>
Some	O
Microsoft	O
CAB	O
(	O
LZX	B-Device
compression	O
)	O
and	O
NSIS	B-Language
(	O
LZMA	B-General_Concept
)	O
installer	O
formats	O
can	O
be	O
opened	O
.	O
</s>
<s>
Similarly	O
,	O
some	O
Microsoft	O
executable	O
programs	O
(	O
.EXEs	O
)	O
that	O
are	O
self-extracting	B-General_Concept
archives	I-General_Concept
or	O
otherwise	O
contain	O
archived	O
content	O
(	O
e.g.	O
,	O
some	O
setup	O
files	O
)	O
may	O
be	O
opened	O
as	O
archives	O
.	O
</s>
<s>
When	O
compressing	O
ZIP	B-General_Concept
or	O
gzip	B-Application
files	O
,	O
7-Zip	B-Language
uses	O
its	O
own	O
DEFLATE	B-Algorithm
encoder	O
,	O
which	O
may	O
achieve	O
higher	O
compression	O
,	O
but	O
at	O
lower	O
speed	O
,	O
than	O
the	O
more	O
common	O
zlib	B-Language
DEFLATE	B-Algorithm
implementation	O
.	O
</s>
<s>
The	O
7-Zip	B-Language
deflate	B-Algorithm
encoder	O
implementation	O
is	O
available	O
separately	O
as	O
part	O
of	O
the	O
AdvanceCOMP	O
suite	O
of	O
tools	O
.	O
</s>
<s>
The	O
decompression	O
engine	O
for	O
RAR	O
archives	O
was	O
developed	O
using	O
freely	O
available	O
source	O
code	O
of	O
the	O
unRAR	B-Application
program	O
,	O
which	O
has	O
a	O
licensing	O
restriction	O
against	O
creation	O
of	O
a	O
RAR	O
compressor	O
.	O
</s>
<s>
7-Zip	B-Language
v15.06	O
and	O
later	O
support	O
extraction	O
of	O
files	O
in	O
the	O
RAR5	B-Application
format	O
.	O
</s>
<s>
Some	O
backup	B-Protocol
systems	O
use	O
formats	O
supported	O
by	O
archiving	O
programs	O
such	O
as	O
7-Zip	B-Language
;	O
e.g.	O
,	O
some	O
Android	B-Application
backups	B-Protocol
are	O
in	O
tar	B-Application
format	O
,	O
and	O
can	O
be	O
extracted	O
by	O
archivers	O
such	O
as	O
7-Zip	B-Language
.	O
</s>
<s>
7-Zip	B-Language
ZS	O
,	O
a	O
port	O
of	O
7-Zip	B-Language
FM	O
with	O
Zstandard	B-Language
.zst	I-Language
(	O
and	O
other	O
formats	O
)	O
support	O
,	O
is	O
developed	O
by	O
Tino	O
Reichardt	O
.	O
</s>
<s>
Modern7z	O
,	O
a	O
Zstandard	B-Language
.zst	I-Language
(	O
and	O
other	O
formats	O
)	O
plugin	O
for	O
7-Zip	B-Language
FM	O
,	O
is	O
developed	O
by	O
Denis	O
Anisimov	O
(	O
TC4shell	O
)	O
.	O
</s>
<s>
7-Zip	B-Language
comes	O
with	O
a	O
file	B-Application
manager	I-Application
along	O
with	O
the	O
standard	O
archiver	O
tools	O
.	O
</s>
<s>
The	O
file	B-Application
manager	I-Application
has	O
a	O
toolbar	O
with	O
options	O
to	O
create	O
an	O
archive	O
,	O
extract	O
an	O
archive	O
,	O
test	O
an	O
archive	O
to	O
detect	O
errors	O
,	O
copy	O
,	O
move	O
,	O
and	O
delete	O
files	O
,	O
and	O
open	O
a	O
file	O
properties	O
menu	O
exclusive	O
to	O
7-Zip	B-Language
.	O
</s>
<s>
The	O
file	B-Application
manager	I-Application
,	O
by	O
default	O
,	O
displays	O
hidden	O
files	O
because	O
it	O
does	O
not	O
follow	O
Windows	B-Protocol
Explorer	I-Protocol
's	O
policies	O
.	O
</s>
<s>
The	O
tabs	O
show	O
name	O
,	O
modification	O
time	O
,	O
original	O
and	O
compressed	O
sizes	O
,	O
attributes	O
,	O
and	O
comments	O
(	O
4DOS	B-Application
descript.ion	O
format	O
)	O
.	O
</s>
<s>
:	O
Same	O
as	O
"	O
Computer	O
"	O
except	O
loads	O
the	O
drives	O
in	O
low-level	O
NTFS	B-Application
access	O
.	O
</s>
<s>
7-Zip	B-Language
supports	O
:	O
</s>
<s>
Encryption	O
via	O
the	O
256-bit	O
AES	B-Algorithm
cipher	I-Algorithm
,	O
which	O
can	O
be	O
enabled	O
for	O
both	O
files	O
and	O
the	O
7z	O
hierarchy	O
.	O
</s>
<s>
WinZip-developed	O
Zip	B-General_Concept
file	I-General_Concept
AES	B-Algorithm
encryption	I-Algorithm
standard	O
is	O
also	O
available	O
in	O
7-Zip	B-Language
to	O
encrypt	O
ZIP	B-General_Concept
archives	I-General_Concept
with	O
AES	B-Algorithm
256-bit	I-Algorithm
,	O
but	O
it	O
does	O
not	O
offer	O
filename	O
encryption	O
as	O
in	O
7z	O
archives	O
.	O
</s>
<s>
Graphical	B-Application
user	I-Application
interface	I-Application
.	O
</s>
<s>
The	O
Windows	O
version	O
comes	O
with	O
its	O
own	O
GUI	B-Application
;	O
however	O
,	O
p7zip	B-Language
uses	O
the	O
GUI	B-Application
of	O
the	O
Unix/Linux	O
Archive	O
Manager	O
.	O
</s>
<s>
Two	O
command-line	B-Application
versions	O
are	O
provided	O
:	O
7z.exe	O
,	O
using	O
external	O
libraries	O
;	O
and	O
a	O
standalone	O
executable	O
7za.exe	O
,	O
containing	O
built-in	O
modules	B-Architecture
,	O
but	O
with	O
compression/decompression	O
support	O
limited	O
to	O
7z	O
,	O
ZIP	B-General_Concept
,	O
gzip	B-Application
,	O
bzip2	B-Application
,	O
Z	B-Device
and	O
tar	B-Application
formats	O
.	O
</s>
<s>
The	O
7za.exe	O
version	O
of	O
7-Zip	B-Language
is	O
available	O
for	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
(	O
including	O
Linux	B-Application
,	O
FreeBSD	B-Operating_System
,	O
and	O
macOS	B-Application
)	O
,	O
FreeDOS	B-Application
,	O
OpenVMS	B-Operating_System
,	O
AmigaOS	B-Application
4	I-Application
,	O
and	O
MorphOS	B-Operating_System
under	O
the	O
p7zip	B-Language
project	O
.	O
</s>
<s>
7-Zip	B-Language
has	O
a	O
LZMA	B-General_Concept
SDK	B-Application
which	O
was	O
originally	O
dual-licensed	B-License
under	O
both	O
the	O
GNU	B-Application
LGPL	I-Application
and	O
Common	O
Public	O
License	O
,	O
with	O
an	O
additional	O
special	O
exception	O
for	O
linked	O
binaries	O
.	O
</s>
<s>
On	O
2	O
December	O
2008	O
,	O
the	O
SDK	B-Application
was	O
placed	O
by	O
Igor	B-Language
Pavlov	I-Language
in	O
the	O
public	O
domain	O
.	O
</s>
<s>
On	O
older	O
versions	O
,	O
self-extracting	B-General_Concept
archives	I-General_Concept
were	O
vulnerable	O
to	O
arbitrary	O
code	O
execution	O
through	O
DLL	O
hijacking	O
:	O
they	O
load	O
and	O
run	O
a	O
DLL	O
named	O
UXTheme.dll	O
,	O
if	O
it	O
is	O
in	O
the	O
same	O
folder	O
as	O
the	O
executable	O
file	O
.	O
</s>
<s>
7-Zip	B-Language
16.03	O
Release	O
notes	O
say	O
that	O
the	O
installer	O
and	O
SFX	O
modules	B-Architecture
have	O
added	O
protection	O
against	O
DLL	O
preloading	O
attack	O
.	O
</s>
<s>
Versions	O
of	O
7-Zip	B-Language
prior	O
to	O
18.05	O
contain	O
an	O
arbitrary	O
code	O
execution	O
vulnerability	O
in	O
the	O
module	B-Architecture
for	O
extracting	O
files	O
from	O
RAR	O
archives	O
(	O
)	O
,	O
a	O
vulnerability	O
that	O
was	O
fixed	O
on	O
30	O
April	O
2018	O
.	O
</s>
<s>
Snapfiles.com	O
in	O
2012	O
rated	O
7-Zip	B-Language
4.5	O
stars	O
out	O
of	O
5	O
,	O
noting	O
,	O
"[its]	O
interface	O
and	O
additional	O
features	O
are	O
fairly	O
basic	O
,	O
but	O
the	O
compression	O
ratio	O
is	O
outstanding	O
"	O
.	O
</s>
<s>
On	O
TechRepublic	O
in	O
2009	O
,	O
Justin	O
James	O
found	O
the	O
detailed	O
settings	O
for	O
Windows	B-Application
File	I-Application
Manager	I-Application
integration	O
were	O
"	O
appreciated	O
"	O
and	O
called	O
the	O
compression-decompression	O
benchmark	O
utility	O
"	O
neat	O
"	O
.	O
</s>
<s>
And	O
though	O
the	O
archive	O
dialog	O
has	O
settings	O
that	O
"	O
will	O
confound	O
most	O
users	O
"	O
,	O
he	O
concluded	O
:	O
"	O
7-Zip	B-Language
fits	O
a	O
nice	O
niche	O
in	O
between	O
the	O
built-in	O
Windows	O
capabilities	O
and	O
the	O
features	O
of	O
the	O
paid	O
products	O
,	O
and	O
it	O
is	O
able	O
to	O
handle	O
a	O
large	O
variety	O
of	O
file	O
formats	O
in	O
the	O
process.	O
"	O
</s>
<s>
Between	O
2002	O
and	O
2016	O
,	O
7-Zip	B-Language
was	O
downloaded	O
410	O
million	O
times	O
from	O
SourceForge	B-Application
alone	O
.	O
</s>
<s>
The	O
software	O
has	O
received	O
awards	O
,	O
In	O
2007	O
,	O
SourceForge	B-Application
granted	O
it	O
community	O
choice	O
awards	O
for	O
"	O
Technical	O
Design	O
"	O
and	O
for	O
"	O
Best	O
Project	O
"	O
.	O
</s>
<s>
In	O
2013	O
,	O
Tom	O
's	O
Hardware	O
conducted	O
a	O
compression	O
speed	O
test	O
comparing	O
7-ZIP	B-Language
,	O
MagicRAR	O
,	O
WinRAR	B-Application
,	O
WinZip	B-Application
;	O
they	O
concluded	O
that	O
7-ZIP	B-Language
beat	O
out	O
all	O
the	O
others	O
with	O
regards	O
to	O
compression	O
speed	O
,	O
ratio	O
,	O
and	O
size	O
and	O
awarded	O
the	O
software	O
the	O
2013	O
Tom	O
's	O
Hardware	O
Elite	O
award	O
.	O
</s>
