(related variations: gz z)

The GNU Zip program is used to compress the size of a single file. If more than one file has to be compressed, they must be tarred together first. The program that does the compression is called gzip, and the gzipped file cannot be used until it has been gunzipped. The gzip program has its origins on UNIX machines, but it has been ported to most other computer types as well and is typically available for free under the terms of the GNU public license. The "gz" form is preferred; the other is considered obsolete as it was frequently confused with the output of the UNIX compress program and deliberately changed to be something more distinctive. Gzip is better at compression than compress.