An operating system is the most important software that runs on a computer. It manages the computer's memory, processes, and all of its software and hardware. Memory management is the process of controlling and coordinating computer memory, assigning portions called blocks to various running programs to optimize overall system performance. Memory management resides in hardware, in the OS (operating system), and in programs and applications.
In hardware, memory management involves components that physically store data, such as RAM (random access memory) chips, memory caches, and flash-based SSDs (solid-state drives).
In the operating system, memory management involves the allocation (and constant reallocation) of specific memory blocks to individual programs as user demands change.