Tar is used to describe both a file format which uses the extension .tar as well as the program used with tar files. Tar files are a collection of one or more files which are usually preceded by a header record that is 512 bytes long, the data is not altered when written but is rounded out to 512 bytes in length by filling any extra space with zeros and at then another two zero filled records are usually added.
It is also possible to compress tar files using the following compressions.
When a tar file has been compressed it will be shown with the filename, extension then the compression technology used, for example compressing a tar file with gzip would be shown as filename.tar.gz
The name tar comes from Taped Archive and was created for use in Unix operating systems.
How to open .tar files?