Virtual memory is an operating-system technique that makes a computer behave as if it has more RAM by moving inactive data to disk, usually in a pagefile or swap area. It lets programs keep running even when physical memory is tight, but disk access is much slower than RAM, so heavy paging can make a system sluggish.
In cyber security, virtual memory matters because it affects performance, stability, and analysis. Malware or a packed process may trigger unusual paging patterns, while defenders use memory forensics and crash dumps to inspect what was resident in RAM and what was swapped out. On low-memory endpoints, reducing memory pressure can also help security tools stay responsive and avoid forcing critical activity onto disk.