A network is a group of two or more computer systems linked together. Examples of computer networks are local-area networks (LANs, i.e. in the same building), wide-area networks (WANs, i.e. computers are farther apart and are connected by telephone lines or radio waves) or campus-area networks (CANs, i.e. computers are within a limited geographic area, such as a campus or military base). For more, read “Who Knows My IP Address?”