How do I compress or uncompress files?

Infrequently accessed files may be compressed to save disk space.

gzip file                 Compresses file to file.gz 
gunzip file.gz            Uncompresses file.gz to file 
gtar xzvf file.tar.gz     Uncompresses file.tar.gz to the contents of file.tar 
compress x y ...          Compresses x, y, ... to x.Z, y.Z, ... 
uncompress x y ...        Uncompresses x.Z, y.Z, ... to x, y, ... 
zcat x.Z y.Z ...          Prints the compressed file(s) to the terminal

See the UNIX manual pages for the above programs by using the 'man', for example 'man gzip'.