Editing Computer memory (section)

=== Virtual memory ===
{{Main|Virtual memory}}
Virtual memory is a system where [[physical memory]] is managed by the operating system typically with assistance from a [[memory management unit]], which is part of many modern [[CPU]]s. It allows multiple types of memory to be used. For example, some data can be stored in RAM while other data is stored on a [[hard drive]] (e.g. in a [[swapfile]]), functioning as an extension of the [[cache hierarchy]]. This offers several advantages. Computer programmers no longer need to worry about where their data is physically stored or whether the user's computer will have enough memory. The operating system will place actively used data in RAM, which is much faster than hard disks. When the amount of RAM is not sufficient to run all the current programs, it can result in a situation where the computer spends more time moving data from RAM to disk and back than it does accomplishing tasks; this is known as [[Thrashing (computer science)|thrashing]].