Virtual memory is an illusion of an extremely large memory that is created by the operating system. It allows a computer to compensate for shortages of physical memory by temporarily transferring pages of data from random access memory (RAM) to disk storage.

How does virtual memory work?

Virtual memory works by dividing memory into small chunks called pages. When a program requests memory, the operating system assigns it a page of memory. If the requested memory is not available in physical memory, the operating system swaps out some pages of memory that are not currently being used and transfers them to a special area of the hard disk called the swap file. This frees up space in physical memory to load the requested page.

When the program needs the swapped-out page again, the operating system swaps it back into physical memory and swaps out another page if necessary. This process is transparent to the program, which continues to operate as if it has access to all the memory it needs.

Advantages of virtual memory:

• It allows programs to run on systems with less physical memory than they would otherwise require.

• It allows multiple programs to run simultaneously, even if the combined memory requirements of all the programs exceed the amount of physical memory available.

• It protects the operating system from crashes caused by poorly written or malicious programs that attempt to access memory outside their allotted space.

Disadvantages of virtual memory:

• It can slow down performance because the operating system has to continually swap pages of memory between physical memory and disk storage.

• It can cause disk thrashing, which is when the operating system spends more time swapping pages of memory than running programs.

• It can be difficult to configure and optimize, especially on systems with multiple processors or complex memory architectures.