1) An archive is a collection of computer files that have been packaged together for backup, to transport to some other location, for saving away from the computer so that more hard disk storage can be made available, or for some other purpose. An archive can include a simple list of files or files organized under a directory or catalog structure (depending on how a particular program supports archiving).
On personal computers with the Windows operating system, WinZip is a popular program that lets you create an archive (a single file that holds a number of files that you plan to save to another medium or send someone electronically) or extract its files. WinZip also compresses the files that are archived, but compression is not required to create an archive. A WinZip archive has the file name suffix ".zip".
In UNIX-based operating systems, the tar (tape archive) utility can be used to create an archive or extract files from one. On mainframe operating systems such as IBM's MVS and OS/390, procedures for archiving or backing up files are often automated as a daily operation.
2) On Web sites as well as in libraries, an archive is a collection of individual publications that are often cataloged or listed and made accessible in some way. Magazines, journals, and newspapers with Web sites sometimes refer to their back issues as an archive.
3) Web and File Transfer Protocol sites that provide software programs that can be downloaded sometimes refer to the list of downloadable files as an archive or as archives.