Virtual Memory in Operating System
Virtual Memory:
Virtual Memory is a technique that if the logical address is greater than the physical address and even also load into the main memory and executes the job.
Example: Demand paging
Demand Paging:
Demand paging is the application of virtual memory, it is the combination of paging and swapping. A page is not loaded into the main memory until it is needed. This scheme is called Demand paging.

Thrashing:
If the number of processes submitted to the CPU for execution is increased, then the CPU utilization will also be increased. But increasing the process continues at a certain time, then the CPU utilization falls sharply and sometimes it reaches zero. This situation is said to Thrashing.