File stored on your hard disk, made up of contiguous disk sectors, which is used to store temporary data in virtual memory system that's used by Windows. If you use several programs at once, Windows will use virtual memory to store the programs it cannot fit into the real RAM chips in your PC. Windows supports permanent and temporary swap files, but a permanent file is faster. You can change the size and the file type from a temporary to a permanent using the Control Panel icon in Windows, and selecting the Enhanced/Virtual Memory option. A permanent swap file is faster than a temporary swap file, but it takes up a section of disk space. A temporary swap file is deleted after it's been used, which is important if you are running short of disk space. If you increase the size of the permanent swap file, you will improve the speed of Windows. But watch out: if the swap file gets too big, you could slow down Windows because it takes so much time to manage the swap file. Stick to the setting that Windows recommends, which it calculates based on the size of hard disk and amount of RAM you have.