Each time you click on a link in a web page or type an address into your web browser you are making a 'request' for a certain document.
That request is handled with the Hyper Text Transfer Protocol (HTTP) and sent over the Internet to the server which holds the document in question.
If all goes well the server responds by sending the document -- usually a web page of text and graphics.
HTTP, IP and TCP explained
HTTP is part of the Internet Protocol (IP) suite. It is used by a 'client' such as a web browser to establish a connection with the server which hosts a particular website. The server waits for incoming requests by monitoring TCP port 80.
TCP has provisions for identifying the requesting computer and for transmitting data with time stamps so that it can be reassembled in the correct order once it arrives at its destination.
A typical request goes like this:
If faq.html is available the server will respond:
TCP send a series of 'packets' of information
The web page is sent via TCP as a series of data packets each with a header that specifies its destination and order in the data stream.
The various packets can all take different paths to reach their destination. Each is sent through a router which polls other routers which are close by.
If a connection with the first router is unavailable the data will be sent through another one.
If not, they will be re-transmitted by the server.
TCP also checks that the data is undamaged. The data is reassembled in the correct order thanks to the sequence number of each data packet. Voila! The web page appears on your computer screen.
Either client or server can close the connection at any time.
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