What is Network?

A Computer Network can be defined as "Two or more computer connected by some means through which they are capable of sharing information." There are many types of Network such as:

1. Local Area Networks

2. Wide Area Networks

3. Metropolitan Area Networks

4. Campus Area Networks

5. Ethernet Networks

6. Token Ring Networks

7. Fiber Distributed Data Interface Networks

8. Asynchronous Transfer Mode Networks

9. Frame Relay networks

10. T1 Networks

11. DS3 Networks

12. Bridged Networks

13. Routed Networks

14. Point to Point Networks

and many names.

If you're old enough to remember the program Laplink, which allowed you to copy files from one computer to another over a special parallel port cable, you can consider that connection a network as well. it wasn't very scalable (Only two computers), or very fast, but it was a means of sending data from one computer to another via a connection.

Networks are often distinguished by their reach. LANs, WANs, MANs, and CANs are all examples of network types defined by their areas of coverage. LANs are, as their name implies, Local to something--Usually a single building or floor. WANs cover broader areas, and are usually used to connect LANs. WANs can span the globe, and there's nothing that says they couldn't go farther. MANs are common in areas where technology like Metropolitan Area Ethernet is possible; they typically connect LANs within a given geographical region such as a city or town. A CAN is similar to a MAN, but is limited to a campus (a campus is uauallly defined as a group of buildings under the control of one entity, such as a college or a single company).

Source:: O'Reilly-Network Warrior (2007) Book