A network is a system of interconnected computers or devices that allows for the exchange of data between linked nodes. The key components of a computer network include nodes, network interface cards, communication media, protocols, routers and switches. There are several types of networks including local area networks (LANs) that connect devices within a short distance, metropolitan area networks (MANs) that span a larger physical area than a LAN, and wide area networks (WANs) that connect geographically dispersed LANs over longer distances. The largest WAN is the Internet.