(1) To replace pages or segments of data in memory. Swapping is a useful technique that enables a computer to execute programs and manipulate data files larger than main memory. The operating system copies as much data as possible into main memory, and leaves the rest on the disk. When the operating system needs data from the disk, it exchanges a portion of data (called a page or segment ) in main memory with a portion of data on the disk.
Swapping is often called paging.
(2) In UNIX systems, swapping refers to moving entire processes in and out of main memory.
(3) When spelled SWAP, an acronym for Shared Wireless Access Protocol.