What is a .ZIP file?
ZIP is a popular archive format widely used on the Internet. Like other archives, .ZIP files are data containers, they store one or several files in a compressed form. After you download a .ZIP file, you need to unpack its contents in order to use it.
How to handle ZIP files
WinRAR provides complete support for all ZIP files, so you can easily create and unpack them. With WinRAR installed on your computer you can download and unpack any ZIP file from anywhere. To extract it's files, just double click on the ZIP file and it will open in WinRAR. Just select all files, press the "Extract To" button, enter a destination path and press "OK". Another way is to click on the ZIP file in Explorer using the right mouse button. Then if you enabled the "Shell integration" option when installing WinRAR, the file context menu will contain the "Extract to ..." option.
ZIP versus RAR
The main advantage of ZIP format is its popularity. The ZIP file format was developed a long time ago and perhaps it is still the most known archive type, so quite a few Internet archives are ZIP files. But the biigest difference is that ZIP cannot create such highly compressed files as RAR does (RAR's encoding program is proprietary). So RAR archives usually provide a noticeably higher compression ratio, better compress / decompress speed than the ZIP file format. Also many important RAR format features (recovery records, strong AES encryption, Unicode names, etc.) are missing in ZIP. For more info see the detailed comparison between RAR and ZIP.