Zip is a file archiver with a high compression ratio. The program supports 7z, ZIP, RAR, CAB, ARJ, LZH, CHM, CPIO, RPM, DEB, GZIP, BZIP2, Z and TAR formats. Compression ratio in the new 7z format is 30-50% better than ratio in ZIP format. Also 7-Zip compresses to ZIP 2-10% better than PKZip and WinZip. 7-Zip has additional powerful command line version and FAR Manager support.
Zip is open source software. Most of the source code is under the GNU LGPL license. The unRAR code is under a mixed license: GNU LGPL + unRAR restrictions.
You can use 7-Zip on any computer, including a computer in a commercial organization. You don't need to register or pay for 7-Zip.