gzip reduces the size of the named files using Lempel–Ziv coding (LZ77). Whenever possible, each file is replaced by one with the extension ‘.gz’, while keeping the same ownership modes, access and modification times. (The default extension is ‘-gz’ for VMS, ‘z’ for MSDOS, OS/2 FAT and Atari.) If no files are specified or if a file name is -, the standard input is compressed to the standard output. gzip will only attempt to compress regular files. In particular, it will ignore symbolic links.
gzip -c file1 file2 > foo.gz
gzip -d foo.gz gunzip foo.gz