7-Zip is a file archiver with high compression ratio.
7-Zip is free software distributed under the GNU LGPL.

The main features of 7-Zip:
High compression ratio in new 7z format with LZMA compression
Supported formats: 7z, ZIP, CAB, RAR, ARJ, GZIP, BZIP2, Z, TAR, CPIO, RPM and DEB
For ZIP and GZIP formats 7-Zip provides compression ratio that is 2-10 % better than ratio provided by PKZip and WinZip
Self-extracting capability for 7z format
Integration with Windows Shell
Powerful File Manager
Powerful command line version
Plugin for FAR Manager
Localizations for 55 languages