The Internet and How It Works

In one sense, detailing the statement in the title would require at least a book. In another sense, it can''t be fully explained at all, since there''s no central authority that designs or implements the highly distributed entity called The Internet.

But the basics can certainly be outlined, simply and briefly. And it''s in the interest of any novice web site owner to have some idea of how their tree fits into that gigantic forest, full of complex paths, that is called the Internet.

The analogy to a forest is not far off. Every computer is a single plant, sometimes a little bush sometimes a mighty tree. A percentage, to be sure, are weeds we could do without. In networking terminology, the individual plants are called ''nodes'' and each one has a domain name and IP address. Connecting those nodes are paths.

The Internet, taken in total, is just the collection of all those plants and the pieces that allow for their interconnections - all the nodes and the paths between them.

Servers and clients (desktop computers, laptops, PDAs, cell phones and more) make up the most visible parts of the Internet. They store information and programs that make the data accessible. But behind the scenes there are vitally important components - both hardware and software - that make the entire mesh possible and useful.

Though there''s no single central authority, database, or computer that creates the World Wide Web, it''s nonetheless true that not all computers are equal. There is a hierarchy. That hierarchy starts with a tree with many branches: the domain system.

Designators like .com, .net, .org, and so forth are familiar to everyone now. Those basic names are stored inside a relatively small number of specialized systems maintained by a few non-profit organizations. They form something called the TLD, the Top Level Domains. From there, company networks and others form what are called the Second Level Domains, such as Microsoft.com.

That''s further sub-divided into www.Microsoft.com which is, technically, a sub-domain but is sometimes mis-named ''a host'' or a domain. A host is the name for one specific computer. That host name may or may not be, for example, ''www'' and usually isn''t. The domain is the name without the ''www'' in front. Finally, at the bottom of the pyramid, are the individual hosts (usually servers) that provide actual information and the means to share it.

Those hosts (along with other hardware and software that enable communication, such as routers) form a network. The set of all those networks taken together is the physical aspect of the Internet.

There are less obvious aspects, too, that are essential. When you click on a URL (Uniform Resource Locator, such as http://www.microsoft.com) on a web page, your browser sends a request through the Internet to connect and get data. That request, and the data that is returned from the request, is divided up into packets (chunks of data wrapped in routing and control information).

That''s one of the reasons you will often see your web page getting painted on the screen one section at a time. When the packets take too long to get where they''re supposed to go, that''s a ''timeout''. Suppose you request a set of names that are stored in a database. Those names, let''s suppose get stored in order. But the packets they get shoved into for delivery can arrive at your computer in any order. They''re then reassembled and displayed.

All those packets can be directed to the proper place because they''re associated with a specified IP address, a numeric identifier that designates a host (a computer that ''hosts'' data). But those numbers are hard to remember and work with, so names are layered on top, the so-called domain names we started out discussing.

Imagine the postal system (the Internet). Each home (domain name) has an address (IP address). Those who live in them (programs) send and receive letters (packets). The letters contain news (database data, email messages, images) that''s of interest to the residents.

The Internet is very much the same.