In computing, tar (derived from tape archive) is both a file format (in the form of a type of archive bitstream) and the name of a program used to handle such files. The format was created in the early days of Unix and standardized by POSIX.1-1988 and later POSIX.1-2001. Initially developed to write data to sequential I/O devices for tape backup purposes, tar is now commonly used to collect many files into one larger file for distribution or archiving, while preserving file system information such as user and group permissions, dates, and directory structures.
The GZ file type is primarily associated with 'Gzip'. Ofter found in a double extension with TAR (e.g., .TAR.GZ) where the tarball is the archive which is then compressed using Gzip.