Tar is a well known file format though many users confuse it to be something that it is not. Tar is an old format evident by its name which stands for Tape Archive. So what are Tar files?



Tar originates from Unix systems and up to this day it is mostly used in that environment. It is very common to see Tar files on a Unix or Linux system but it is pretty rare to see such files on Windows systems. Tar was developed as a format for supporting tape archiving or tape backup. The sequential one pass nature of tapes derived many of the attributes of the format. As a backup tool Tar was designed to store not just files but also the complete folder structure in which they are stored and the security parameters such as access rights for the files and folders.

Tar files are many times confused to be compressed files. In fact Tar files are only an archiving or packing format. In other words Tar files define how files and folder structures can be packed into one big archive file and how that file can then be stored or transferred and later on unpacked to the exact original structure. Tar files are not compressed and the Tar format does not define any compression features.

Although Tar files are not compressed files there is a great value in compressing data for either backup or transmission purposes. Tar files are very commonly used in conjunction with a separate compression utility in the Unix environment always the GZip utility. GZip allows the compression of one file. In most cases Tar files are created and then passed through the GZip filter for compression. Such files are also known by their compounded extension .tar.gz.

To open and extract data from a .tar.gz file one needs to first run the Ungzip software which decompresses the file. The output of the Ungzip software is the original Tar file. One can then use any Untar utility in order to unpack the Tar file content back to its original folder structure and original files.

Tar is can now be used in other environment than Unix and Linux. Tar utilities for Windows are very common and in fact most of Windows archiving utilities such as the well known WinZIp WinRAR and 7Zip support the open and reading of files from Tar archives and also the creation of new Tar files. Tar files can be compressed using other utilities rather than the GZip and in fact in the windows environment it is not rare to see Tar files being compressed into Zip files.

The usage of Tar together with the GZip compression utility is so common that many archiving software utilities now allow the direct processing of such files. In other words when you open a .tar.gz file in those utilities it will automatically recognize that it is a Tar file that was compressed with GZip. The utility will Ungzip the Tar file and then unpack the underlying Tar file in one action. You will immediately be presented with the content of the files and folders in the Tar instead of needing to first uncompress the GZip and then unpack the Tar.