RAR is a proprietary archive file format that supports data compression, error recovery and file spanning. It was developed in 1993 by Russian software engineer Eugene Roshal and the software is licensed by win RAR. The name RAR stands for Roshal Archive.

Windows computers don't have a baked-in ability to open RAR files. If you double-click or double-tap a RAR file without having specific software installed to open it, you'll probably see one of the following messages: "Windows cannot open this file" or "How do you want to open this type of file (.rar)?".

RAR is actually the regular format of an archive program called WinRAR. The only problem with using WinRAR is that it's not free! Before you run off and buy it, please know that there are plenty of free RAR openers that can do the exact same thing but at zero cost. Of all the un-RAR tools out there, 7-Zip is probably the best one.