A RAR file (short for a Roshal Archive Compressed file) is a compressed file, or data container, that holds one or more other files and folders inside of it.
RAR file needs special software to open and "extract" out the contents. If you downloaded the RAR file from the internet, you need to unpack its contents in order to use it.
RAR files can also be protected with a password and encrypted so that the contents inside of them stay hidden unless you know the password.
It was developed by a Russian software engineer, Eugene Roshal. The RAR software is licensed by win. rar GmbH.
Other than compression it also supports error recovery and files spanning.
WinRAR 5.0 is the latest version of RAR which support maximum compression dictionary size upto 1GB