WAN (Wide Area Network) connects machines over widely separated geographical locations. A WAN usually consists of various packet switches installed at various points on the network to carry the signals to long distances.
LAN (Local Area Network) span shorter distances usually with an enterprise or within the enterprise department. Since LAN cover shorter distances, they provide high speed transmission.
MAN (Metropolitan Area Network) span intermediate geographic areas and operate at medium to high speeds. MAN have lesser delay than the WANs and provide high speeds via high speed switches.