gzip (GNU zip) is a compression utility designed to be a replacement
for 'compress'. Its main advantages over compress are much better
compression and freedom from patented algorithms. The GNU Project
uses it as the standard compression program for its system.
gzip currently uses by default the LZ77 algorithm used in zip 1.9 (the
portable pkzip compatible archiver). The gzip format was however
designed to accommodate several compression algorithms. See below
for a comparison of zip and gzip.