".rar" files or WINRAR files are compressed files, just like zip files.
The only difference is the ability of the WINRAR compressor to compress files way better than normal zip files in shorter span of time.
And other notable utility is that it allows the users to spit files.
It is recommended to use WINRAR over WINZIP.
So if you encounter any .rar file then please use WINRAR to de-compress it.
Download WINRAR setup here :