Well simply put any allocation that's not really needed any time soon but is also not freed. Swap let's you use that. In terms of what benefits from that most

Well simply put any allocation that's not really needed any time soon but is also not freed. Swap let's you use that. In terms of what benefits from that most modern programs are actually surprisingly flexible in memory allocation. Anything with a garbage collection behind the scenes will flush more often if needed. Having swap to push the non needed programs out let's GC based programs keep allocations longer which is intended to enable reuse