Swapping a process

Swapping is the act of storing or loading a process into or out of memory. It's important to mention that this has nothing to do with virtual memory management.

Swapping only occurs in operating systems with no virtual memory management.

In operating systems where we implement virtual memory management with the help of a MMU, we would use a different technique called paging.

Missing process

A process that is currently stored outside our memory, can not be executed because the CPU only has direct access to a process inside our memory. Therefore, we need to first load the entire process from the place where it's stored (some drive) into memory, before we can start to execute.