(v.) (1) To copy files to a long-term storage medium for backup. Large computer systems often have two layers of backup, the first of which is a disk drive. Periodically, the computer operator will archive files on the disk to a second storage device, usually a tape drive.
On smaller systems, archiving is synonymous with backing up.
(2) To compress a file.
(2) A file that contains one or more files in a compressed format.
(adj.) In DOS systems, the archive attribute marks files that have been modified since the last backup.