A Wan is a large area network that expands in a geographical area, such as a country or a continent. It is known also as a communication system that connects computer networks such as LANs (local area network) and MANs (metro area network). The connections go through local, national or international areas public or privately, using generally phones lines, referred to as POST, or employing PSTN (public switched telephone network) or fibre optics, creating the link between networks located in different facilities.
A WAN differs from a LAN in several important ways. Most WANs (like the Internet) are not owned by any one organization but rather exist under collective or distributed ownership and management. WANs tend to use technology like ATM, Frame Relay and X.25 for connectivity over the longer distances.
These networks contain a collection of machines to execute some programs which are called hosts. These are connected to networks that have communication through routers with each LAN and a WAN interface. Remote access is something vital for the companies and users because it allows you to have mobility and work through different areas. Also it gives the benefit to get better business out of your area.