In computing, tar (derived from tape archive) is both file format (in the form of a type of archive bitstream) and the name of the program used to handle such files. The format was standardized by POSIX.1-1998 and later POSIX.1-2001. Initially developed as a raw format, used for tape backup and other sequential access devices for backup purposes, it is now commonly used to collate collections of files into one larger file, for distribution or archiving, while preserving file system information such as user and group permissions, dates, and directory structures.
tar's linear roots can still be seen in its ability to work on any data stream and its slow partial extraction performance, as it has to read through the whole archive to extract only the final file. A tar file (somefile.tar), when subsequently compressed using a compression utility such as gzip, bzip, or (formerly) compress, produces a compressed tar file with a filename extension indicating the type of compression (e.g.: somefile.tar.gz). A .tar file is commonly referred to as a tarball, which may be compressed or not.