An archive file is a file that is composed of one or more computer files along with metadata. Archive files are used to collect multiple data files together into a single file for easier portability and storage, or simply to compress files to use less storage space. Archive files often store directory structures, error detection and correction information, arbitrary comments, and sometimes use built-in encryption.
Zip is the most-widely used format, used by the Windows operating system and more recently by OSX as well. RAR is also a very popular and flexible format. Unix uses the tar file format, while Linux uses the tar and gz format.