We have now covered all the basic concepts using a computer. In this chapter we are going to cover the concepts related to networking and using the Internet.
A network is a way of connecting two or more computers together so that they can share peripherals (hardware like printers) and data. The most common form of network uses Ethernet. Ethernet is a system of data transfer that uses two different kinds of wire, the older one being like a cable television wire and the newer one being like telephone wire. The newer one is faster and uses an end called RJ-45, which looks like a fat telephone cable end. Normally, computers are plugged into a hub, or switch using an internal piece of hardware called an Ethernet card or simply a network card and one of these cables. Then they can all communicate with each other.
Once the computers can communicate, each item (i.e. printer or folder) that needs to be accessed on the network must be shared, allowing it to be visible to the other computers. Any shared item may be blocked off from general use by a password. One of the other benefits of networks is email (electronic mail). Email allows users to send messages and files to each other. When a new message is received it goes into the users inbox for storage until it is read, so that a user may receive mail while away from the computer.
Ethernet networks create what is called Local Area Networks(LANs). This means that they are used within one area (i.e. a house or business building) and that is it. All the computers in that area may be connected, but no one else. This can be a problem depending on what you want to do, and a larger network could open up immense possibilities. Enter the Internet. In 1957, just after the USSR launched Sputnik, the American government created ARPA, a scientific research branch for the military. In 1969 ARPA decided to attempt the creation of a national computer network for communications by the military. They did not want to use any standard system, however, not just because of the distance, but because of the fear of nuclear attack. They wanted a network where there was not central hub that could be taken out, but where all remaining parts would function if any other part were destroyed.
After their success, the idea spread. Different government and educational institutions started connecting into the network. Because they all used the same protocol (a set of rules that computers use to communicate, in this case TCP/IP) and the same wires that carried telephone across the country as soon as they plugged in it was the same network. Soon different institutions were creating their own servers (computers that store information meant to be accessed on a network). By 1989 there were more than 100 000 servers on what was becoming known as ‘the Internet’. After the Cold War the American government no longer needed a specifically protected portion of this network they had started for their own and the Internet became completely public domain.