WAN may seem a bigger version of [[LAN]] but in reality its structure is quite different. Two LANs must exist in order to create a WAN. The WANs built by [[ISP]]s provide connectivity from LAN to Internet. WANs do not directly connect one computer to another, which is the role of [[LAN]].<ref>[http://www.makeuseof.com/tag/technology-explained-wide-area-network-wan-tutorial/ MakeUseOf]</ref> Local Area Networks are connected by a device named router which then connects them to WAN.<ref>[http://compnetworking.about.com/od/basicnetworkingconcepts/a/network_types.htm ComputerNetworking at About.com]</ref> In WAN the data transmission is generally provided by telephone lines
. However it can also be connected through Packet Switching, Circuit Switching, Cell Relay or leased lines.<ref>[http://www.wisegeek.com/what-is-a-wide-area-network.htm WiseGeek]</ref><ref>[http://www.makeuseof.com/tag/technology-explained-wide-area-network-wan-tutorial/ MakeUseOf]</ref> The main features of each connectivity option are given below:
Lines''' provide Point-to-Point connection between Local Area Networks.
'''Circuit switching''' creates a dedicated circuit path between end points as used in Dial-Up connections.
'''Packet switching''' creates packets of data which are then transferred through different variable length virtual circuits.
'''Cell relay''' also creates packets but these packets are tranferred through fixed length virtual circuits.<ref>[http://www.answers.com/topic/wide-area-network Answers]</ref>