Topic summary
Pagefile.sys
Extracted from the Wikipedia article Memory paging.
Windows NT
The file used for paging in the Windows NT family is pagefile.sys. The default location of the page file is in the root directory of the partition where Windows is installed. Windows can be configured to use free space on any available drives for page files. It is required, however, prior to Windows Vista and Windows Server 2008 for the boot partition (i.e., the drive containing the Windows directory) to have a page file on it if the system is configured to write either kernel or full memory dumps after a Blue Screen of Death. Windows uses the paging file as temporary storage for the memory dump. When the system is rebooted, Windows copies the memory dump from the page file to a separate file and frees the space that was used in the page file.