WinRAR is a 32-bit Windows version of the RAR archiver - a powerful tool which allows you to create, manage and control archive files.
RAR is a general purpose archiving and compression program competing with/replacing programs such as PKZip, ARJ, and others. RAR offers significantly improved compression ratios, easier use and a cheaper price as well as supporting long file names, disk spanning, and self-extracting file creation.
More info:
hxxp://www.rarlab.com/