1. To temporarily move data (programs and/or data files) from random access memory to disk storage (swap out), or back (swap in), to allow more programs and data to be processed than there is physical memory to hold it. Also called Virtual Memory. From I-gloss

2. An important aspect of all operating systems is a feature called "virtual memory". This allows the OS to take unused pieces of memory and write them to disk, then free up the block of memory just written so that another active application can use it. Whenever somebody needs that block again, the operating system will automatically restore it from the disk. Of course, it will then have to free up another block to do so by writing that block to the disk. This technique is generally called "swapping" or "paging". The word "swap" reflects the fact that inactive blocks of memory are being switched with active blocks from the disk. The word "paging" reflects the fact that a common name for a block of memory is "page". The name of the file on the disk that an OS uses for swapping is called the "swapfile" or "pagefile". Key point: A lot of security depends upon the fact that memory is secure: the OS protects applications from reading other application's memory, and that when the computer is turned off, the memory is erased. Therefore, applications can safely store passwords in clear-text in memory. Swapping defeats this, because the memory pages that store the passwords may have been swapped to the disk. Someone with physical access to the machine can turn it off, steal the disk, and run the pagefile through analysis programs in order possibly retrieve passwords. From Hacking-Lexicon

3. to move information from a fast-access memory to a slow-access memory (`swap out'), or vice versa (`swap in'). Often refers specifically to the use of disks as `virtual memory'. From Linux Guide @FirstLinux

4. vt. 1. [techspeak] To move information from a fast-access memory to a slow-access memory (`swap out'), or vice versa (`swap in'). Often refers specifically to the use of disks as `virtual memory'. As pieces of data or program are needed, they are swapped into core for processing; when they are no longer needed they may be swapped out again. 2. The jargon use of these terms analogizes people's short-term memories with core. Cramming for an exam might be spoken of as swapping in. If you temporarily forget someone's name, but then remember it, your excuse is that it was swapped out. To `keep something swapped in' means to keep it fresh in your memory: "I reread the TECO manual every few months to keep it swapped in." If someone interrupts you just as you got a good idea, you might say "Wait a moment while I swap this out", implying that a piece of paper is your extra-somatic memory and that if you don't swap the idea out by writing it down it will get overwritten and lost as you talk. Compare page in, page out. From Jargon Dictionary