Local area network (LAN) — A network that ranges over a small area, generally less than a few thousand feet
Wide area network (WAN) — A large network that can span thousands of miles
Campus area network (CAN) — An intermediately sized network
A network that is composed of a linked group of networks is called an internetwork. For example, your machine might be part of a network within your building and part of an internetwork that connects your local network to similar networks across the country. Because the difference between a network and an internetwork is generally invisible to the user, the term network is used in this guide to refer to both networks and internetworks.
Networked machines use a network protocol, or common network language, to communicate. A network protocol ensures that information is transmitted to the appropriate location on the network. An internetwork protocol, sometimes referred to as a relay, links networks together.