WAN (Wide Area Network)   When an  individual Company or Organization has locations that are separated by large geographical distances, it will be a matter of necessity to connect these individual locations so as to share, exchange and manager data or communication. To achieve this, the organisation needs a Telecommunication Service Provider (TSP) to interconnect the LANs at the different locations. Telecommunications Service Providers manage large area networks that can span long distances.  TSPs transported voice and data communications on separate networks. These networks that connect LANs in geographically separated locations are referred to as Wide Area Networks (WANs). See the image below:       Here are the three major characteristics of WANs: WANs generally connect devices that are separated by a broader geographical area than can be served by a LAN. WANs use the services of carriers, such as telephone companies, cable companies, satellite systems, and network providers. WANs use serial connections of various types to provide access to bandwidth over large geographic areas.                                                                                        Recommended Cisco Networking Books

WAN Devices         Cabling Network Devices         Straight through Cables         Cross Over Cables         Virtual Private Network (VPN)         Point-to-Point (PPP)         Frame Relay