What are .RAR files and how do I use them?
In short, a RAR file is a container file that contains one or more files in compressed form. RAR files can be used to split a large file into many smaller, easier-to-download files, or to put a set of many small files into a single, larger, easy-to-download file.

For a full definition of .RAR files, please visit the following link: http://www.rarlab.com/rar_file.htm

To create .RAR files, you will need a program such as:

However, to freely extract .RAR files, most newsreaders are configured to do that automatically. Alternatively, you can download 7-zip to do that for you.