Files with the .ZIP extension contain an archive of compressed data, namely one or multiple files or catalogs, including their file structures, that have been compressed. If there are multiple files, they are compressed separately, which enables them to be subjected to different compression methods and unpacked independently from one another.

The ZIP format is supported by most file compression and decompression software, as well as natively in the Windows and Mac OS X operating systems. Both systems allow for compression and decompression in the context menu. By default, a new archive in Windows is called Folder.Zip. The format was devised in 1989 by Phil Katz, but was initially only used in the PKZIP software created by PKWARE, Inc.