File with a .GZ extension contains a compressed archive of one or many files. GZ files are compressed with the GNU ZIP algorithm and they are utilised by Unix type systems. If the extension contains also a .tar.gz or .tgz extension, the file is compressed with a TAR package – tarball. In such situation, first, it has to be decompressed and then extended with a TAR tool or the access has to be acquired.

GZ archive is created with the GZIP tool, which is a standard element of most of Unix systems. GZ files are also utilised by many other Windows, Mac or Linux tools, however, they are not of the same format or same algorithm as the ones used in ZIP compression.