In computing, the tar file format is a type of archive file format: the Tape ["ARchive"] format. These files are produced by the ["Unix"] command tar and were standardized by POSIX.1-1998 and later POSIX.1-2001.
It is used widely to archive and unarchive files, which means to accumulate a large collection of files into a single archive file (packer), while preserving FileSystem information such as user and group permissions, dates, and ["directory"] structures.
Commonly a tar file is referred to as a tarball .
In the Unix philosophy of "one job, one program", it does not support compression directly. If you then want to compress your archive, you use a separate program that is specialised in compression. tar is most commonly used in tandem with an external compression utility such as ["gzip"] or ["bzip2"], since it has no built in data compression facilities. These compression utilities generally only compress a single file, hence the pairing with tar, which can produce a single file from many files.
==Filename extension *.tar , for tar file. *.tar.gz or .tgz (only when compressed by gzip) *.tar.bz2 or .tbz (only when compressed by bzip2)