About .RAR File Format
One of the most popular archive formats, .RAR and its associated program WinRAR, was developed by Eugene Roshal (the name RAR stands for Roshal Archive).
WinRAR is famous for its “infinite 40-day trial”, where a free version of the program claims that it will stop working in 40 days after installation, but doesn’t actually do so.
RAR archives can only be created in WinRAR, but can also be opened by other software, such as 7-Zip.
Link:
7-Zip Home Page
WinRAR Home Page