7-Zip can also open any file format that uses a supported compression method. For instance, it is possible to open MSI files in 7-Zip that include the files to be installed with the file itself (otherwise, the files are stored in CAB files, also supported). This makes 7-Zip a good tool to check if a file is an archive.
For ZIP and gzip files, 7-Zip uses a modified implementation of the DEFLATE algorithm that is tuned for higher compression levels at the expense of speed. This implementation is also used in the AdvanceCOMP tools.
The native 7z file format is an open, modular architecture which allows it to contain files compressed
Unicodeusing different algorithms.7-Zip supports a number of other compression (and non-compression) archive formats. These supported formats include ZIP, Microsoft cabinet (CAB) files, RAR, ARJ, gzip, bzip2, LHA, tar, cpio, rpm and Debian deb archives.-Zip also supports ISO CD/DVD images.

Platforms: Win95 , Win98 , WinME , WinNT 3.x , WinNT 4.x , Windows2000 , WinXP

System requirements: 16 MB RAM, 15 MB Disk Space