Let's say that you are sitting at your computer, surfing the Web, and you get a call from a friend who says, "I just read a great article! Type in this URL and check it out! It's at http://www.byronbayonline.net/internet.html". So you type that URL in to your browser and press return. And magically, no matter where in the world that URL lives, the page pops up on your screen!

At the most basic level possible, the following diagram shows the steps that brought that page to your screen:

Your browser formed a connection to a Web server, requested a page and received it. If you want to get into a bit more detail, here are the basic steps that occurred behind the scenes:

The browser broke the URL into 3 parts:

• The protocol ("http")

• The server name ("www.byronbay0nline.net")

• The file name ("internet.html")

• The browser communicated with a name server to translate the server name "www.byronbayonline.net" into an   IP Address, which it uses to connect to the server machine.

• The browser then formed a connection to the server at that IP address on port 80.

• Following the HTTP protocol, the browser sent a GET request to the server, asking for the file   "http://www.byronbayonline.net/internet.html".

• The server then sent the HTML text for the Web page to the browser.

• The browser read the HTML tags and formatted the page onto your screen.

The complex process

The secret of the Net is a network protocol called TCP/IP--that is, a kind of coding system that lets computers electronically describe data, like the contents of this story, to each other over the network.

The term actually refers to two separate parts: the transmission control protocol (TCP) and the Internet protocol (IP). Every computer that hooks to the Internet understands these two protocols and uses them to send and receive data from the next computer along the network.

TCP/IP creates what is called a packet-switched network, a kind of network intended to minimize the chance of losing any data that is sent over the wires.

First, TCP breaks down every piece of data--such as an email message or instructions from a Java applet--into small chunks called packets, each of which is wrapped in an electronic envelope with Web addresses for both the sender and the recipient. The IP protocol then figures out how the data is supposed to get from point A to point B by passing through a series of routers--sort of like regular mail passes through several post offices on its way to a remote location.

Each router examines the destination addresses of the packets it receives and then passes the packets on to another router as they make their way to their final destination. If your email was broken into ten packets, then each of those may have traveled a completely separate route. But you'll never know it, because as the packets arrive, TCP takes over again, identifying each packet and checking to see if it's intact. Once it has received all the packets, TCP reassembles them into the original. (See Figure.)

TCP/IP is the most important of a long list of Internet protocols. It is sometimes used as a global term to describe additional protocols, including simple mail transfer protocol (SMTP), file transfer protocol (FTP), and Telnet protocol.