What makes a WAN different from a LAN and MAN?

The terms you mention in your question are frequently come by in today's network books and discussions. WAN (Wide Area Network) is used to describe large scale networks that extend across areas, cities and even countries around the globe. International companies with offices around the world use various methods to interconnect them between each other, allowing them to freely exchange data, voice and other services. The speed in which these huge networks run at are relatively small, mainly due to the high costs involved. On the other side, LAN (Local Area Networks) are found in every type of company, office and home. These "small" networks (compared to WAN networks) are fast, much cheaper and easy to maintain in most situations. Today, we have LAN networks running at speeds that touch the 10 Gbps mark, making them lightening fast. The equipment required to run these networks is not considered that expensive, plus, they are easy to maintain. MAN (Metropolitan Area Networks) are somewhere in between WAN and LAN networks. They can spread over a city or two and connect smaller office (LAN) networks between them. The equipment required to run them can be a bit expensive and the speeds they usually reach are the 50-100 Mbps mark depending on the way they interconnect. Each type of network uses their own special set of protocols in order to ensure they operate in the most efficient way, without outages and problems. These protocols vary depending on the type of network. For example, LAN networks usually run the Ethernet Protocol allowing local nodes/workstations to communicate between each other. STP (Spanning Tree Protocol) is also another frequently used protocol that makes sure no network loops are created between switches. MAN and WAN protocols may use routing protocols whose job is to make sure everyone knows about the available networks and how they can be reached. In WAN protocols, you also won't find traditional equipment such as switches or hubs. They only exist in the LAN networks. WAN and MAN networks make use of more sophisticated equipment such as routers that are designed to help connect between each other at high speeds. Routers are found at the boundary of a LAN network, connecting them to larger networks (WANs).