Your computer uses random-access memory (RAM) to run system software and application programs. Each time you open an application program, your computer reserves a portion of memory for the program. That portion of memory stays in reserve until you quit the program.

To see how much memory is available:

•	Switch to the Finder, then open the Apple menu and choose About This Computer.

The About This Computer window includes the following information:

•	Built-in Memory: the amount of random-access memory (RAM) installed in your computer
•	Virtual Memory: the amount of disk space and the name of the disk currently used for virtual memory
•	Largest Unused Block: the largest chunk of memory available to open an application program

The About This Computer window also shows how much memory has been reserved for each open application program and how much of that memory is actually being used by the program.

You can increase the amount of memory available for using programs by turning on "virtual memory" (hard disk space the computer uses as if it were memory). Disk space used for virtual memory is not available for storing files.

Tip: For more information about items in this window, open the Help menu and choose Show Balloons, then point to the item you want to learn more about.