A GZ file is an archive file compressed by the standard GNU zip (gzip) compression algorithm. It contains a compressed collection of one or more files and is commonly used on Unix operating systems for file compression.

Gzip is standardly installed on most Unix operating systems and is recognized by most file decompression utilities for Mac, Windows, and Unix. Gzip compression, while similar to .ZIP files, should not be confused with ZIP compression. NOTE: Files with the extension ".tar.gz" or ".tgz" are known as "tarballs," which are .TAR files compressed with Gzip compression. These files must first be decompressed, then expanded using a TAR utility. They are commonly found on Unix systems.