Zlib
From Genome Analysis Wiki
The zlib allows applications to conveniently read and write gzip compatible files. It was developed by Jean-Loupe Gailly and Mark Adler.
Linux
zlib is included by default in most Linux distributions. If it is not available on your system, you could download and install a copy from http://www.zlib.net or use a package manager like yum or apt to install it on your system. A typical command line request to install zlib might look like this:
yum install zlib-devel apt-get install zlib-devel
Windows
On Windows, zlib is available through the MinGW, msys and CygWin collections of utilities and libraries, which are designed to facilitate porting of applications from Linux to Windows.