Basic Computer Network

Introduction

A network is a group of things that are connected together. In a computer network, the things that are connected are computers, of course. A computer network can be as small as two computers but there is no maximum size, and many networks have hundreds or thousands of computers.

There are three main reasons for connecting computers in a network:

1. Share information. This can be messages such as e-mail, or it can be files that are stored on one computer and used by someone at a different computer.

2. Share resources. A printer that can be accessed from different computer systems is a shared resource. So is an Internet connection used by more than one computer.

3. Centralized control. In most offices, the management determines what the computers may be used for and what kind of resources and support they need. This is much easier to deal with if the computers are connected.

Types of Networks

Just as there is no limit to the number of systems in a network, there is also no limit to the geographical size of a network. As a practical matter though, there are some structural differences between a network of computers all in the same room, and a network connecting computers in Los Angeles to ones in Sydney Australia.

The most common network includes computers that are close together, usually in the same building or office. This is called a Local Area Network, abbreviated LAN.

The computers in a LAN are usually connected with cable made up of pairs of wires, but faster (and more expensive) cables are made from glass fibers, called fiber optic cable. A network may even use radio waves, in which case it is a wireless LAN.

When the computers being connected are far apart, typically in different cities, it is called a WAN or Wide Area Network. The connection is usually done with special high-speed lines leased from the phone company, but it is also possible to connect over an ordinary phone line using a device called a modem. It’s slow, but possible. Accessing a network through a phone line and modem is called a dial-up connection.

The biggest of all networks is the Internet. The backbone of the Internet consists of powerful computers all over the world with high-speed connections between them. Individual computers such as yours then connect to this backbone through an Internet Service Provider or ISP.