File compression is important because it makes transferring files and backing up documents more efficient.

You may have seen compressed files before, like .zip files (or .hqx files for Mac). A common Unix compression format has a .tar extension. From this, a further compressed format ends with a .tar.gz extension (sometimes shortened to a .tgz extension). These compressed files are often called "tarballs".

To create a tarball, we use:

gtar czvf foo.tar.gz

This will compress all the files in the current directory and add them to a tarball with called foo.tar.gz.

To unpack a tarball called foo.tar.gz, we use:

gtar xzvf foo.tar.gz

This extracts all the files in the tarball to the current directory.