Expandability is the capability of a computer system to accommodate more memory, additional disk drives, peripherals, or other devices that enhance its usefulness or performance. Synonymous with an upgrade. Thanks to recent expansion bus technologies such as USB and IEEE 1394 (FireWire), most of today’s personal computer systems are easily expanded; however, computer shoppers should note that some system upgrades may require physical slots (such as expansion slots or memory slots) on the computer’s motherboard.