7Zip (archiving and compression)

www.7-zip.org

The free file archiving software. At this point all of the popular zip file tools are pretty much at the same level as far as features, file compatibility and interface, so just use the free one. WinRAR has an old clunky interface, but is still quite good. And of course WinZIP is still the stalwart in the industry, but aside from the nicer interface doesn’t have any features to set it apart from the rest.

Alternate choice: WinRAR