7-Zip is a file archiver with a high compression ratio . 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 . 7-Zip works for Windows 7, Vista, XP, 2008, 2003, 2000, NT, ME, and 98 .
Most of the source code is under the GNU LGPL license .
The unRar code is under a mixed license with GNU LGPL + unRAR restrictions . Check the license for details .
7-zip can be utilized on multiple platforms including Windows 7, Vista, XP, 2008, 2003, 2000, NT, ME, and 98 
7-zip can be used to open an ISO Image File.
In order to secure a transfer along untrusted lines, 7-Zip can encrypt containers with AES-256.
For securing fixity: 7-Zip records checksums on compression and verifies them on decompression.
7-Zip can handle containers larger than 2 GigaByte (unlike tools for the genuine ZIP format).
And there is a port of the command line version to Linux/Unix .