The Web is based on a set of rules for exchanging text, images, sound, video, and other multimedia files, which is collectively known as HTTP, or hypertext transfer protocol. Web pages can be exchanged over the Net because browsers (which read the pages) and Web servers (which store the pages) both understand HTTP.

But everything would still be chaos if the Web didn't have an addressing scheme that every computer on the network understands. An IP address is a 4- to 12-digit number that identifies a specific computer connected to the Internet. The digits are organized in four groups of numbers (which can range from 0 to 255) separated by periods. Depending on how your ISP assigns IP addresses, you may have one address all the time or a different address each time you connect. Web servers have the same kind of addresses: if you type http://204.162.80.183/ in your browser, you'll get the same result as if you had typed http://www.cnet.com/.

Internet domain names are the next level of Internet addressing, just as the street name is followed by the city and state. Domain names create a single identity for a series of computers used by a company or an institution. So while there may be 38 servers at a given company, each with its own IP address, they all share a common domain name, such as CNET.COM.

The domain name identifies all the computers in a group. But if you want to get to a specific page stored on any of those computers, you'll need an even more precise address. That's why every Web page on the Internet, and even the objects you see displayed on Web pages, has its own unique address, known as a Uniform Resource Locator (URL), which tells your browser exactly where to go on the server to find a page.