>[!tldr] Physical Frame Number (PFN) > When using [[Paging system|paging]] the [[Operating system (OS)|operating system]] breaks up [[Physical memory|physical memory]] into [[Frame (networks)|frames]]. The *physical frame number* is an index in the [[Operating system (OS)|operating system]] abstraction of [[Random Access Memory (RAM)|RAM]] which acts as one contiguous block. This with an offset can get mapped to a location on [[Random Access Memory (RAM)|RAM]] by the [[Memory controller|memory controller]].