How does an Internet Work?

The thing that characterizes the Internet is how data is transferred from one computer to another. Did you ever wonder what magical things go on behind the scenes that results in a Web page being displayed on your screen seconds after you request it? How does the data get from one side of the world to the other?
Here’s what happens to a piece of data (e.g., a Web page) when it is transferred over the Internet: 
•It is broken up into a whole lot of same-sized pieces (called packets). 
•A header is added to each packet that explains where it came from, where it should end up and how it fits in with the rest of the packets. 
•Each packet is sent from computer to computer until it finds its way to its destination. Each computer along the way decides where next to send the packet. This could depend on things like how busy the other computers are when the packet was received. The packets may not all take the same route. 
•At the destination, the packets are examined. If there are any packets missing or damaged, a message is sent asking for those packets to be resent. This continues until all the packets have been received intact. 
•The packets are reassembled into their original form. 
Each computer connected up to the Internet has software called TCP/IP (Transmission Control Protocol/Internet Protocol) which is responsible for receiving, sending and checking packets. TCP/IP is the ‘glue’ of the Internet.
 Say, for example, you are sending a message from Mumbai to New York (USA), to a server named nyork.org. The message will be broken up into packets of approximately 1500 bytes, and some may travel from VSNL here to the MCI router in the US, some may travel to Madras and then to the MCI router, and so forth. There is no predetermined path and individual packets of the same message may follow different paths. It all depends on the traffic at that node, at that moment of time.
        As the packets reach nyork.org, they are put together as in the original message and delivered to the given address. In order to accomplish the task of messaging across a network, computers use a networking protocol. Taking the analogy of diplomacy, the relations and interactions between’s the representatives of different countries follow a set of rules laid down by tradition and treaty, which is called diplomatic protocol. Similarly, all computers wanting to talk to each other have to conform to a standard set of rules defined in the networking protocol