A Computer network that spans relatively small area is called Local Area Network (LAN). Most LANs are confined to small building or group of buildings. However one LAN can be connected to other LANs over any distance via telephone lines and radio waves. A system of LANs can be cconnected in this way is called Wide Area Network (WAN)
Most LANs can connect workstations and personal computers. Each node (individual computer) in a LAN has its own CPU with which it executes programs, but it is also can able to access data and devices anywhere in the LAN. This means that many users can able to share expensive devices, such as laser printers, as well as data. Users can also use the LAN to communicate with each other, by sending e-mails or engaging in chat sessions or can able to play games together
Metropolitan Area Network or MANs are large computer networks usually spanning a campus or a city. They usually use wireless infrastructure or optical fiber communications to their sites
For instance a university or college may have MAN that joins together many of the local area networks (LANs) situated around site of a fraction of square kilometer. Then from their MAN they could have several Wide Area Network (WAN) links to other universities or the internet. Specially this type of MAN is known as campus area networks