File compressed or "zipped" using Zip compression, a common type of compression in which every file in the archive is compressed separately; supported by most file compression/decompression programs.
Windows users can create ZIP archives by right-clicking a file and selecting "Send to → Compressed (zipped) Folder." Mac OS X users can create ZIP archives by right-clicking a file and selecting "Compress [filename]."
Common ZIP Filenames:
New Compressed (zipped) Folder.zip - The name Microsoft Windows gives to new ZIP files created via the context menu (right-click and choose New → Compressed (zipped) Folder).
Game file used by MAME arcade video game emulators; may contain the entire contents of the arcade game data, or may be supplemented by .CHD arcade hard disk file, which is required in order to play the game; stored in a compressed .ZIP format.
MAME ROMs are sometimes difficult to load properly due to file format and emulation software differences. Therefore, some emulators are distributed with a tool that verifies whether a ROM can be loaded or not.