How to "unzip" Zipped files

How do you open or "unzip" a ZIP file? If you have the latest version of Windows (ME, XP or newer ones), or Apple OS, just double-click on the zip file or folder, which will look something like this: 

Notice the zipper? That is Windows' way of telling you that the file or folder has been zipped. Once you double-click on that file or folder, it should open just as if it were a regular file or folder on your computer.