Necessity of Internet
It is important to understand what a network is and the importance of network. Simply put, a network is a collection of interconnected devices (such as computers, printers, etc.). To understand the importance of networks, let us look at how things worked before networks were created. For this, consider a large multinational company that sells food products in a time when networks did not exist.
Let us call this company Sri Mother International Ltd. Imagine the amount of information such as sales, inventory, etc. required by the management of the company to make everyday decisions. To get this information they will need to call their local offices. Their local offices will need to mail or fax printed reports or even send media (floppies!) through the postal service. By the time the mail is received, the data is already days old. Even if reports are faxed, it will be a cumbersome task to consolidate all reports. This task also increases chance of human error since large numbers of reports are manually collated. This is just one part of the equation. You also need to consider the information required by the local offices. They also need various data from the head office and other offices around the world.
Now consider the same company, but in the present time with all their offices interconnected. They would use a single application around the world that takes advantage of their global network. The data from all offices would be instantly stored at the central location and with a single click, the management team can see data from around the world in any format they like. This data would also be real-time. This means that they see it, as its happening. Since the data is centralized, any office location can see data pertaining to any location.
As you can see, the cost, time and effort involved in transferring data was much higher without networks. So networks decrease cost, time, and effort and thereby increase productivity. They also help in resource optimization by helping to share resources. A simple example of resource sharing is a printer, shared between many different computers in a typical office.
Now that you know how beneficial networks are, its time to look at different types of network.