RAR is the new Linux version of WinRAR, the famous Windows file compressor, which also allows GNU/Linux users to compress and extract files in this format.
It integrates seamlessly with the desktop that you're using, adapting to the compression tool included by default in your system.
The only drawback you might run into with RAR is that it is shareware (trial version), which is unusual for GNU/Linux. But there's no other alternative because at the moment there's no other way to create RAR files on Linux.
The trial period lasts 40 days.