Write a brief note on demand paging.

A demand paging is alike to a paging system with swapping. The Processes reside on the secondary memory while we want to implement a process and we swap it into the memory. Relatively than swapping the entire process into memory though we use a lazy swapper. A lazy swapper not at all swaps a page into memory unless that page will be needed. Ever since we are now viewing a process as a sequence of pages, relatively than as one large contiguous address space, use of swap is principally incorrect. A swapper manipulates entire processes where a pager is concerned with the individual pages of a process. We therefore use pager relatively than swapper in connection with demand paging.