Files that end with the extension ".zip" are archive files that contain a collection of files in a compressed format. Compression can dramatically reduce the size of files that are archived. In order to access the files inside a zip file, the zip file needs to be uncompressed, or "extracted."

Both Windows XP and OS X have built-in zip file support. For help with creating and extracting zip files, see the related articles at the bottom of this page.

Commercial compression software such as WinZip (PC) and Stuffit (Mac) are also available, however we recommend that you use the tools native to the operating system because they are easy to use and come at no cost.