How Does the Internet Work?
Each of the activities mentioned in the section describing what one can do on the Internet requires that computers exchange information. Computers take turns sending and receiving information. When a computer is sending information, it is known as the "source"; when it is receiving information, it is known as the "destination." (The same computer can be both a source and destination at different times. This is especially clear when one thinks of sending and receiving e-mail.)
Every computer on the Internet has a unique Internet "address" that identifies it from among the millions of computers. The Internet has specialized computers between the source and destination located at network inter-connection points. These computers are known as "routers." The routers understand how to use a computer's address to appropriately point information from one computer to another over the Internet.
In an exchange of information the following occurs:
- The source finds the address of the destination.
- The source contacts the destination and says "hello".
- The destination responds back with a "hello" of its own.
- The source tells the destination that it has information to send. * The destination tells the source that it is ready to receive the information.
- The source breaks the information into small pieces called packets and sends each packet on its way to the destination.
- The routers guide each packet to the destination.
- The destination takes the packets and puts them back together to form the information.
The destination tells the source that it has received the information and asks the source if it has anything more to send.
If the source says no, the destination will say "good bye"unless it has something to send back. If it does, it will break the information into packets and send them.
Once both end users are done "talking", they say both say "goodbye".
Clearly our simplified introduction to this section did not explain many steps in this process, such as how a computer discovers the address of another computer or how packets are divided and reassembled. Fortunately, these are specifics that people using the Internet never really need to deal with!
Source R. Plzak