Metropolitan area networks or MANs are large computer networks usually spanning a campus or a city. They typically use optical fiber connections to link their sites. For instance a university or college may have a MAN that joins together many of their local area networks (LANs) situated around site of a fraction of a square kilometer. Then from their MAN they could have several wide area network (WAN) links to other universities or the Internet. Some technologies used for this purpose are ATM, FDDI and SMDS.

These older technologies are in the process of being displaced by Gigabit Ethernet-based MANs in most areas. MAN links between LANs have been built without cables using either microwave, radio, or infra-red free-space optical communication links. Several notable networks started as MANs, such as the Internet peering points MAE-West and MAE-East and the Sohonet media network.