http://www.computerhope.com/jargon/s/swapfile.htm

A file stored on the computer hard disk drive that is used as a temporary location to store information that is not currently being used by the computer RAM. By using a swap file a computer has the ability to use more memory than what is physically installed in the computer. However, users who are low on hard disk space may notice that the computer runs slower because of the inability of the swap file to grow in size.

It is perfectly normal for the swap file or page file to grow in size, sometimes growing several hundred megs in size. Below is a listing of common Microsoft operating system swap file information; however, it is important to realize that this information may vary. Finally, by default the swap files are hidden.

documented on: 2008-03-30