Winzip is useful for:

• Backing up a set of files . Since the files are placed in a single zip file and since this zip file is compressed, the files are easier to move and they take up less space.
• Sending a set of files to someone via email . Many people have limits file size when sending an attached file. You can "zip" a bunch of files and attach them to an email, and the total size might be much less than that of the original files (the amount of compression depends on the file type. Most graphics files do not compress at all).
• Many programs that you can download from the Internet are in zip format . The original (unzipped) program files are usually several files, including a "setup" program that "installs" the program on your hard disk. Installing the program means getting the program ready to run, which usually includes things like writing an entry for the program into the Start menu. If you do not have Winzip or a similar program, you can't unzip these programs, so, you can't install them.