9 - Computer Networks

Networks in general are systems that facilitate movement. The movement could be of people, water, products, electricity, and information to name a few. Our world is full of networks. The transit network, the postal network, the road network, the telephone network, and the food supply network are some examples of networks around us. Networks are useful because they facilitate movement and reduce cost. The computer network essentially facilitates the movement of data, just like the road network facilitates the movement of vehicles. In the road network, rules are established to facilitate the flow of traffic and equipment; for example, traffic lights and traffic signs are used to control the flow of traffic to improve the efficiency of the network. A traffic system where there are no rules would be a very inefficient system. Imagine the time it would take to go from one end of the city to another in a traffic system without any rules. Networks also save money. Consider the electrical power supply network that brings power to your home. If each home was fed with a line directly from the power generation plant then the cost of the overall system will be enormous due to the large amount of wiring required. By using shared wires the cost of the system could be reduced without compromising on the functionality.

Computer networks evolved out of the need for information transfer between computers. Once the principles of communication between peripheral devices and the computer was established, the next logical step was getting computers to communicate or transfer data between them. Before computer networks came into existence, data could be transferred from one computer to another through some kind of storage device, provided a common storage standard was used by both computers. The trouble with using a physical means of transferring information is that it is slow, cumbersome, and inefficient. An example of this approach is data transfer using a USB storage device. When a file is created and saved on the USB storage device, and then moved to another computer and worked on, the information has been transferred from one computer to another successfully.  This method is practical when the computers are relatively close to each other. When the physical distance between computers increases, then this method of information transfer becomes impractical. To solve this problem of information transfer computer networks were designed and built.