This is a method of making a computer appear to have more primary memory than it has really has physically. For instance a PC might have 2Gb of RAM as primary memory, but virtual memory of 4Gb.
The operating system sets aside part of secondary storage - such as a hard disk or flash memory stick - to act as a temporary memory store. This area is called the 'Page File' or 'Swap File'. The operating system keeps a record of all the processes and data currently in main memory (RAM) and if it fills up too much, it will begin to store less-used chunks in the swap file located on disk. This chunk is called a 'page' and is sized so that it matches effectively with the sector size of the hard disk. All this work is done automatically by the operating system.
If even virtual memory is filling up, you may get a message popping from the task bar saying 'Your computer is low on virtual memory'. So it is time for you to close down a few applications.
Challenge see if you can find out one extra fact on this topic that we haven't already told you
Click on this link: Virtual Memory