Virtual memory
Beginner
A trick that gives every program its own made-up set of addresses. The chip quietly turns them into real memory addresses.
Novice
Each program uses virtual addresses that the hardware translates, page by page (often 4 KiB), into physical addresses using page tables the operating system keeps in memory. It isolates programs and lets memory be moved or shared.
Expert
Translation by multi-level radix page tables (e.g., four 9-bit levels plus a 12-bit offset in x86-64 and RISC-V Sv48), cached in TLBs and page-walk caches. Larger pages (2 MiB, 1 GiB) cut walk depth and raise TLB reach.
Explained in Caches and coherence (Architectures).
See also: TLB (translation lookaside buffer).