What is a WAN?

• A WAN (Wide Area Network) is a network spanning a large distance or broad area (e.g. across metros, cities, countries, continents)

A sample WAN  layout is given below:

A typical WAN

• Typically, any network hop that is larger than 10 km is classified as a WAN, but this distance is not very strictly adhered to.
• Even the last mile link that connects a home network to a local ISP (Internet Service Provider) is considered  as a WAN link.
• A WAN connects multiple networks ( LANs/MANs, CANs) spread across long distances together
• A WAN link is a wired or wireless telecommunication link that has the capability to carry data over long distances.
• It is usually not owned by a single administrative domain.
• Due to the distance factor,  data transfer rates are lower and delays higher for a WAN, when compared to LAN
• Internet is the largest WAN, spanning the world, connecting all the public data networks.
• A WAN network may either be a point-to-point link, connecting two remote networks, or it may be a switched WAN network, involving multiple WAN switches connecting multiple networks.
• DSL, cable, SONET, T1/E1, Wi-Max are examples of point-to-point WAN network.
• X.25, Frame Relay, ATM, MPLS are examples of Switched WAN networks.

What is a Metropolitan Area Network?

• A MAN (Metropolitan Area Network) is a network that spans across a city or a metro.

A sample MAN layout is given below

A MAN

• A MAN usually spans multiple buildings or even a city (between 5 to 10 km). For e.g. a MAN can connect multiple campuses of the same university spread across different parts of the city. 
• A MAN usually spans an area larger than LAN but lesser than a WAN (E.g: Metro Ethernet Network).
• Can be owned by a single body or by multiple bodies