The extension stands for "Roshal Archive." It is a proprietary compression format that allows multiple files to be bundled together into a smaller, more portable package.
: A popular, free, open-source alternative for extracting RAR files .
Whenever you download archives from the internet, safety is paramount. While the RAR format itself isn't harmful, it can be used to hide malicious code. Follow these steps for any file like this: How To Open, Create, and Convert RAR Files - AVG Antivirus