This information was obtained from http://www.harlequin.com/mm/reference/glossary/m.html
"Operating system memory management is concerned with using the memory management hardware to manage the resources of the storage hierarchy and allocating them to the various activities running on a computer. The most significant effect of OS memory management on many systems is virtual memory, which creates the illusion that every process has more memory than is actually available. However, OS memory management is also concerned with memory protection and security, which help to maintain the integrity of the operating system against accidental damage or deliberate attack. It also protects user programs from errors in other programs."
See also: MemoryManagementLinks