1. A single file containing one or (usually) more separate files plus information to allow them to be extracted (separated) by a suitable program.

Archives are usually created for software distribution or backup. tar is a common format for unix archives, and arc or pkzip for ms-dos and microsoft windows.

2. To transfer files to slower, cheaper media (usually magnetic tape) to free the hard disk space they occupied. This is now normally done for long-term storage but in the 1960s, when disk was much more expensive, files were often shuffled regularly between disk and tape.

3. archive site.