Virtual Memory

Problem

Every process wants memory. But physical RAM is shared, finite, and applications shouldn't directly manipulate each other's memory.

Solution — Virtual Memory

Each process sees its own virtual address space. 
Process A virtual memory ─┐
                          → physical memory
Process B virtual memory ─┘
The operating system and hardware translate virtual addresses into physical memory mappings.
Core idea: virtual memory gives processes isolated logical memory independent of physical RAM layout.