The concepts of LAN and WAN are important ones in computer networks, and critical to keep straight.

A simple way to conceptualize of what a Wide Area Network is to think of it as everything on a network beyond the immediate building in which one is in. The network in a building such as a house or a school is the ["Local Area Network"("LAN")](LANs

Another key concept to keep in mind is that generally the traffic permitted around the LAN is monitored and filtered minimally, if at all. In other words traffic that might be stopped at the firewall (e.g., pornography; dubious email attachments that might contain a virus) can flow readily around the local network from computer to computer. In theory a laptop could be turned into a temporary server that could serve unwanted content to other computers on the local network provided such content already existed on the laptops hard drive