Files with the RAR file format are basically the archive files that are developed by the WinRAR file archiving application. The WinRAR program takes a collection of files or large files and compresses these files into one archive file.
Compressed files make it a lot easier for the users to share the files over the Web or through email. For instance, when you need to send multiple files through email, you can compress them into one RAR file and send the email with one attachment rather than multiple ones. As the WinRAR archiver application creates as an archive, the files come up with a RAR extension. This file format is very much similar to the ZIP format, however, it makes use of a different compression algorithm.
In addition to the problem described above, i.e. the lack of the appropriate application to support the .RAR file, there may be several reasons that cause problems with opening and operation of the data format:
A quite common problem is the lack of application in the appropriate version. Even if you have an application, with the help of which you should open the .RAR file, you may have a problem with it because of its version. Perhaps in previous versions the application has not yet supported the .RAR file, so download the update and check again.
If you have already installed the appropriate application, and it is the correct version, the file may not open correctly, because the operating system does not have information that this program supports the file. So you need to "show" which program the computer should use. To do this:
It also happens that the file you want to open is corrupt and therefore there is no such possibility. In this situation, you should find its different version, or ask a person from whom you got, to send it again. You can also try to find more informations about this file extension here.