An instructional website on Internet literacy for teachers

Overview of the Internet How does it work? This ability of computers and networks all over the world to share information was made possible by two important communication protocols - the Transmission Control Protocol (TCP) and the Internet Protocol (IP). Together they are often referred to as TCP/IP, and together they make the Internet known as a "packet-switched network.". A good analogy will be the postal service. Your computer is both your address and post office. To send a message to another computer you need to put the address of your destination, too.When you transmit, your message travels through cable lines or signals, in the case of wireless technologies. However, your message does not travel in one piece. It is first broken down into numbered, bite-size chunks called "packets" and sent separately through different routes, and then recombined again in their original form at their destination by Transmission Control Protocol. The Internet Protocol handles how these packets are routed. The packets are placed in separate IP "envelopes" and are sent through a series of switches or routers.  Speed and efficiency are essential, as you will soon find out. Many breakthroughs in Internet and computer technologies are guided by the principle of sending and receiving data in the shortest time possible. The data is broken down into packets for faster transmission. As the packets travel in IP envelopes routers examine the addresses of these envelopes and determine the most efficient path for sending each packet to the nearest available router until these reach their final destination. Since the traffic load on the Internet constantly changes every second, the packets may travel in different routes and arrive in different order. At the their destination the TCP will reassemble the packets into their original form according to their numbered order. If a packet is missing the TCP determines that the file or message was corrupted in transit, and will request for retransmission.  Here's another analogy. You have a big family who are traveling from one country to attend a reunion in another country. There are not enough seats on the plane to accommodate everyone so the TCP breaks up everybody in different planes (IP). These flights take different routes and make different stops. It is likely that the passengers in each flight have different destinations. At each of these stops or airports, the router checks the destination of every passenger's ticket and directs each to the next available flight towards their final destination. The members of the convention group arrive at their final destination separately. To regroup them the TCP will do a headcount making sure everybody is accounted for, and then usher them out of the airport in proper order, that is, grandpa first, grandma second, eldest child next, and so on.
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