There are many organizations have a substantial number of computers in operation which are often located far apart. For example, a company with many factories may have computers at each location to keep track of inventories, monitor productivity and for doing local payroll. Initially these computers may have worked in isolation from other computers, but at some point company management may have decided to connect them to be able to extract and correlate the information about the entire company.
I will explain you little bit clearly about how the computer networks helps companies to reduce the expenditure and increase the reliability and scalability.
First goal is “tyranny of geography”. With computer networks, All computer programs, equipment and especially data will be available to anyone on the network without regard to physical location of the resource and the user. In other words, the mere fact that a user happens to be 1000s of kilo meters away from his data should not prevent him from using the data as though they were local.
The second goal is to provide high reliability by having alternative sources of supply. For example, all files could be replaced on two or three computers, so if one of them is unavailable due to a hardware failure the other copies could be used. In addition, the presence of multiple CPUs means that if one goes down, the other may be able to take over the work, although at reduced performance. The ability to continuing the operation in the case of hardware problems is most important factor for military, banking, air traffic control, nuclear reactor safety and for many other applications
Saving money is the third goal by establishing computer networks at companies. Small computers have a much better price and performance ratio than large ones. Mainframes are room sized computers are ten times faster than personal computers but they cost a thousand times more. This imbalance caused many system designers to build systems consisting of personal computers one per user and keeping data on one more file server machines. In this arrangement user are called clients and the whole arrangement is called client server model. In the client-server model, communication generally takes in the form of a request message from the client to the server asking for some work to be done. The server then does the work and sends back the reply. Usually there are many clients using small number of servers. So the total cost of the IT infrastructure will be reduced by implementing computer networks at companies.
4ht goal is scalability. The ability to increase the system performance gradually as the workload grows just by adding more processors. With the centralized mainframes, when the system is full, it must be replaced by larger one, usually at great expense and even greater disruption to the users. With the client-server model, new clients and new servers can be added as and when required.
5th goal is powerful communication medium. Computer network can provide a powerful communication medium among widely separated employees. Using a computer network it is very easy for two or more people who live far apart to write a report together. When one worker makes a change to an online document, the others can see the change immediately, instead of waiting several days for a letter. Such a speedup makes cooperation among far-flung groups of people easy where it previously had been impossible. In the long run, the use of computer networks to enhance human-to-human communication will probably prove more important than technical goals such as improved reliability.