Final answer:
With demand paging, pages are only loaded into main memory when they are actually needed by a program. This method of memory management conserves physical memory and improves efficiency. It works alongside page replacement algorithms to manage memory resources effectively.
Step-by-step explanation:
With demand paging, a page is brought into main memory only when a reference is made to a location on that page. Demand paging is a method of memory management used in modern operating systems where pages of data are only loaded into physical memory when they are needed, rather than preloading all of the possible pages a program might use.
This technique is used to conserve the amount of physical memory and to reduce the number of page transfers between main memory and secondary storage, leading to more efficient use of memory and reduced load times for applications.
Demand paging works in conjunction with a page replacement algorithm, which decides which pages to remove from memory if there is not enough space to accommodate new requests.
When a program tries to access a page that is not currently in memory, a page fault occurs, triggering the operating system to load the required page into memory, possibly replacing an existing one depending on the page replacement strategy employed.