What Does Memory Swapping Mean?
Memory swapping is a memory reclamation method wherein memory contents not currently in use are swapped to a disk to make the memory available for other applications or processes. The exact state or "page" of memory is copied to the disk to make the data contiguous and easy to restore later.
Techopedia Explains Memory Swapping
Memory swapping is done by the OS kernel or, in the case of virtualized environments, by the hypervisor. It is actually an "expensive" process in regard to its overall impact on the system performance since moving data to and from the disk has considerable overhead. The more applications requiring the system to do memory swapping, the slower the performance becomes due to the increased overhead. In this case, increasing the amount of physical RAM would be the best course of action rather than allowing the system to do constant data juggling between the disk and the memory.