<s>
Zlib	B-Language
(	O
or	O
"	O
zeta-lib	O
"	O
,	O
)	O
is	O
a	O
software	B-Library
library	I-Library
used	O
for	O
data	B-General_Concept
compression	I-General_Concept
.	O
</s>
<s>
zlib	B-Language
was	O
written	O
by	O
Jean-loup	O
Gailly	O
and	O
Mark	O
Adler	O
and	O
is	O
an	O
abstraction	B-Application
of	O
the	O
DEFLATE	B-Algorithm
compression	I-Algorithm
algorithm	I-Algorithm
used	O
in	O
their	O
gzip	B-Application
file	B-General_Concept
compression	I-General_Concept
program	O
.	O
</s>
<s>
zlib	B-Language
is	O
also	O
a	O
crucial	O
component	O
of	O
many	O
software	O
platforms	O
,	O
including	O
Linux	B-Operating_System
,	O
macOS	B-Application
,	O
and	O
iOS	B-Application
.	O
</s>
<s>
It	O
has	O
also	O
been	O
used	O
in	O
gaming	O
consoles	O
such	O
as	O
the	B-Operating_System
PlayStation	I-Operating_System
4	I-Operating_System
,	O
PlayStation	B-Operating_System
3	I-Operating_System
,	O
Wii	B-Device
U	I-Device
,	O
Wii	B-Operating_System
,	O
Xbox	B-Device
One	I-Device
and	O
Xbox	B-Operating_System
360	I-Operating_System
.	O
</s>
<s>
The	O
first	O
public	O
version	O
of	O
Zlib	B-Language
,	O
0.9	O
,	O
was	O
released	O
on	O
1	O
May	O
1995	O
and	O
was	O
originally	O
intended	O
for	O
use	O
with	O
the	O
libpng	B-Language
image	O
library	O
.	O
</s>
<s>
It	O
is	O
free	B-Application
software	I-Application
,	O
distributed	O
under	O
the	O
zlib	B-License
License	I-License
.	O
</s>
<s>
zlib	B-Language
compressed	B-General_Concept
data	I-General_Concept
are	O
typically	O
written	O
with	O
a	O
gzip	B-Application
or	O
a	O
zlib	B-Language
wrapper	O
.	O
</s>
<s>
The	O
wrapper	O
encapsulates	O
the	O
raw	O
DEFLATE	B-Algorithm
data	O
by	O
adding	O
a	O
header	O
and	O
trailer	O
.	O
</s>
<s>
This	O
provides	O
stream	O
identification	O
and	O
error	O
detection	O
that	O
are	O
not	O
provided	O
by	O
the	O
raw	O
DEFLATE	B-Algorithm
data	O
.	O
</s>
<s>
The	O
gzip	B-Application
header	O
,	O
used	O
in	O
the	O
ubiquitous	O
gzip	B-Application
file	O
format	O
,	O
is	O
larger	O
than	O
the	O
zlib	B-Language
header	O
,	O
as	O
it	O
stores	O
a	O
file	O
name	O
and	O
other	O
file	B-Application
system	I-Application
information	O
.	O
</s>
<s>
,	O
zlib	B-Language
only	O
supports	O
one	O
algorithm	O
,	O
called	O
DEFLATE	B-Algorithm
,	O
which	O
uses	O
a	O
combination	O
of	O
a	O
variation	O
of	O
LZ77	O
(	O
Lempel	O
–	O
Ziv	O
1977	O
)	O
and	O
Huffman	B-General_Concept
coding	I-General_Concept
.	O
</s>
<s>
This	O
is	O
also	O
the	O
algorithm	O
used	O
in	O
the	O
Zip	B-General_Concept
archive	I-General_Concept
format	I-General_Concept
.	O
</s>
<s>
zlib	B-Language
provides	O
facilities	O
for	O
control	O
of	O
processor	O
and	O
memory	O
use	O
.	O
</s>
<s>
For	O
example	O
,	O
if	O
the	O
data	O
contain	O
long	O
lengths	O
of	O
repeated	O
bytes	O
,	O
the	O
run-length	B-Algorithm
encoding	I-Algorithm
(	O
RLE	O
)	O
strategy	O
may	O
give	O
good	O
results	O
at	O
a	O
higher	O
speed	O
.	O
</s>
<s>
Errors	O
in	O
compressed	B-General_Concept
data	I-General_Concept
may	O
be	O
detected	O
and	O
skipped	O
.	O
</s>
<s>
Today	O
,	O
zlib	B-Language
is	O
something	O
of	O
a	O
de	O
facto	O
standard	O
,	O
to	O
the	O
point	O
that	O
zlib	B-Language
and	O
DEFLATE	B-Algorithm
are	O
often	O
used	O
interchangeably	O
in	O
standards	O
documents	O
,	O
with	O
thousands	O
of	O
applications	O
relying	O
on	O
it	O
for	O
compression	O
,	O
either	O
directly	O
or	O
indirectly	O
.	O
</s>
<s>
The	O
Linux	B-Operating_System
kernel	I-Operating_System
,	O
where	O
zlib	B-Language
is	O
used	O
to	O
implement	O
compressed	O
network	O
protocols	O
,	O
compressed	O
file	B-Application
systems	I-Application
,	O
and	O
to	O
decompress	O
the	O
kernel	B-Operating_System
image	O
at	O
boot	O
time	O
.	O
</s>
<s>
libpng	B-Language
,	O
the	O
reference	O
implementation	O
for	O
the	O
PNG	O
image	O
format	O
,	O
which	O
specifies	O
DEFLATE	B-Algorithm
as	O
the	O
stream	O
compression	O
for	O
its	O
bitmap	O
data	O
.	O
</s>
<s>
libwww	B-Protocol
,	O
an	O
API	O
for	O
Web	O
applications	O
like	O
Web	B-Application
browsers	I-Application
.	O
</s>
<s>
The	O
Apache	B-Application
HTTP	I-Application
Server	I-Application
,	O
which	O
uses	O
zlib	B-Language
to	O
implement	O
HTTP/1.1	B-Protocol
.	O
</s>
<s>
Similarly	O
,	O
the	O
cURL	B-Language
library	O
uses	O
zlib	B-Language
to	O
decompress	O
HTTP	O
responses	O
.	O
</s>
<s>
The	O
OpenSSH	B-Language
client	O
and	O
server	O
,	O
which	O
rely	O
on	O
zlib	B-Language
to	O
perform	O
the	O
optional	O
compression	O
offered	O
by	O
the	O
Secure	B-Protocol
Shell	I-Protocol
protocol	I-Protocol
.	O
</s>
<s>
The	O
OpenSSL	B-Language
and	O
GnuTLS	B-Application
security	O
libraries	O
,	O
which	O
can	O
optionally	O
use	O
zlib	B-Language
to	O
compress	O
TLS	B-Protocol
connections	O
.	O
</s>
<s>
The	O
FFmpeg	B-Library
multimedia	O
library	O
,	O
which	O
uses	O
zlib	B-Language
to	O
read	O
and	O
write	O
the	O
DEFLATE-compressed	O
parts	O
of	O
stream	O
formats	O
,	O
such	O
as	O
Matroska	O
.	O
</s>
<s>
The	O
rsync	B-Application
remote	O
file	O
synchronizer	O
,	O
which	O
uses	O
zlib	B-Language
to	O
implement	O
optional	O
protocol	O
compression	O
.	O
</s>
<s>
The	O
dpkg	B-Language
and	O
RPM	B-Application
package	I-Application
managers	I-Application
,	O
which	O
use	O
zlib	B-Language
to	O
unpack	O
files	O
from	O
compressed	O
software	B-Application
packages	I-Application
.	O
</s>
<s>
The	O
Apache	B-Application
Subversion	I-Application
and	O
CVS	B-Application
version	B-Architecture
control	I-Architecture
systems	I-Architecture
,	O
which	O
use	O
zlib	B-Language
to	O
compress	O
traffic	O
to	O
and	O
from	O
remote	O
repositories	O
.	O
</s>
<s>
The	O
Apache	B-General_Concept
ORC	I-General_Concept
column-oriented	O
data	O
storage	O
format	O
use	O
ZLib	B-Language
as	O
its	O
default	O
compression	O
method	O
.	O
</s>
<s>
The	O
Git	B-Application
version	I-Application
control	I-Application
system	I-Application
uses	O
zlib	B-Language
to	O
store	O
the	O
contents	O
of	O
its	O
data	O
objects	O
(	O
blobs	O
,	O
trees	O
,	O
commits	O
and	O
tags	O
)	O
.	O
</s>
<s>
The	O
PostgreSQL	B-Application
RDBMS	O
uses	O
zlib	B-Language
with	O
custom	O
dump	O
format	O
(	O
pg_dump	O
-Fc	O
)	O
for	O
database	O
backups	O
.	O
</s>
<s>
The	O
class	O
System.IO.Compression.DeflateStream	O
of	O
the	O
Microsoft	B-Application
.NET	I-Application
Framework	I-Application
2.0	O
and	O
higher	O
.	O
</s>
<s>
The	O
"	O
deflate	B-Algorithm
"	O
utility	O
in	O
TORNADO	O
as	O
part	O
of	O
VxWorks	B-Operating_System
Operating	O
System	O
made	O
by	O
Wind	O
River	O
Systems	O
uses	O
zlib	B-Language
to	O
compress	O
boot	O
ROM	O
images	O
.	O
</s>
<s>
zlib	B-Language
is	O
also	O
used	O
in	O
many	O
embedded	O
devices	O
,	O
such	O
as	O
the	O
Apple	O
iPhone	B-Device
and	O
Sony	B-Operating_System
PlayStation	I-Operating_System
3	I-Operating_System
,	O
because	O
the	O
code	O
is	O
portable	O
,	O
liberally	O
licensed	O
,	O
and	O
has	O
a	O
relatively	O
small	O
memory	O
footprint	O
.	O
</s>
<s>
A	O
commonly	O
used	O
library	O
built	O
on	O
an	O
old	O
codebase	O
,	O
zlib	B-Language
is	O
also	O
frequently	O
forked	B-Application
by	O
third-parties	O
that	O
claim	O
improvements	O
to	O
this	O
library	O
:	O
</s>
<s>
Intel	O
has	O
a	O
high-performance	O
fork	B-Application
of	O
zlib	B-Language
.	O
</s>
<s>
CloudFlare	B-Application
maintains	O
a	O
high-performance	O
fork	B-Application
with	O
"	O
massive	O
"	O
improvements	O
.	O
</s>
<s>
zlib-ng	O
is	O
a	O
zlib	B-Language
replacement	O
fork	B-Application
for	O
"	O
next	O
generation	O
"	O
systems	O
.	O
</s>
<s>
It	O
removes	O
workaround	O
code	O
for	O
compilers	O
that	O
do	O
not	O
support	O
ANSI	O
C	B-Language
,	O
integrates	O
Cloudflare	B-Application
and	O
Intel	O
optimizations	O
,	O
adds	O
hardware	B-General_Concept
acceleration	I-General_Concept
(	O
SIMD	B-Device
and	O
intrinsic	B-Application
functions	I-Application
)	O
,	O
and	O
uses	O
code	O
sanitizers	O
,	O
fuzzing	O
,	O
and	O
code	B-Application
coverage	I-Application
to	O
help	O
find	O
bugs	O
.	O
</s>
