Simplify the following text for a Grade 8 native English-speaking person.
Original: In a computer operating system that uses paging for virtual memory memory management , page replacement algorithms decide which memory pages to page out ( swap out , write to disk ) when a page of memory needs to be allocated .
Simplified: Certain operating systems use paging to get virtual memory . This means that a part of the hard disk or a file is used so that the applications or the operating system see more memory that is actually there .