Can you explain how the swap function works in the context of virtual machines?

In the context of virtual machines, the swap function is used to extend available RAM by allocating space on the disk (swap file or swap partition). When physical memory (RAM) runs out, less frequently used pages are moved to swap, freeing RAM for active processes.

This allows the virtual machine to continue operating without crashes, although access to data in swap is slower than in RAM. Thus, swap serves as a backup memory, preventing processes from crashing due to lack of RAM.

Example: if a virtual machine with 4 GB of RAM starts using more memory than available, the OS will move some data to swap, for example, 2 GB of disk space, to ensure the operation of applications.