1.4 Basic Networking Terminology
1.4.5 Wide area networks
As computer use in businesses grew, it soon became apparent that even LANs were not sufficient. In a LAN system, each department, or business was a kind of electronic island. What was needed was a way for information to move efficiently and quickly from one business to another.

The solution was the creation of wide area networks (WANs). WANs interconnected LANs, which then provided access to computers or file servers in other locations. Because WANs connected user networks over a large geographical area, they made it possible for businesses to communicate with each other across great distances. As a result of being networked or connected, computers, printers, and other devices on a WAN could communicate with each other to share information and resources, as well as to access the Internet.

Some common WAN technologies are:

  • modems
  • ISDN (Integrated Services Digital Network)
  • DSL (Digital Subscriber Line)
  • Frame relay
  • ATM (Asynchronous Transfer Mode)
  • The T (US) and E (Europe) Carrier Series: T1, E1, T3, E3, etc.
  • SONET (Synchronous Optical Network)