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Some observers claim that the Internet works so well because it was designed to survive a nuclear attack. Not so. The people who built the Internet insist that they weren’t nearly as concerned about nukes as they were about making communication among researchers reliable, even when a backhoe severed an underground phone line or one of the key computers ground to a halt.

As far as I’m concerned, the Internet works so well because the engineers who laid the groundwork were utter geniuses. Their original ideas from 60 years ago have been through the wringer a few times, but they’re still pretty much intact. Here’s what the engineers decided:

 No single computer should be in charge. All the big computers connected directly to the Internet are equal (although, admittedly, some are more equal than others). By and large, computers on the Internet move data around like kids playing hot potato — catch it, figure out where you’re going to throw it, and let it fly quickly. They don’t need to check with some übercomputer before doing their work; they just catch, look, and throw.

 Break the data into fixed-size packets. No matter how much data you’re moving — an email message that just says “Hi” or a full-color, life-size photograph of the Andromeda galaxy — the data is broken into packets. Each packet is routed to the appropriate computer. The receiving computer assembles all the packets and notifies the sending computer that everything came through okay.

 Deliver each packet quickly. If you want to send data from Computer A to Computer B, break the data into packets and route each packet to Computer B by using the fastest connection possible — even if that means some packets go through Bangor and others go through Bangkok.

Taken together, those three rules ensure that the Internet can keep on functioning no matter what happens. If a chipmunk eats through a line, any big computer that’s using the gnawed line can start rerouting packets over a different one. If the Cumbersome Computer Company in Cupertino, California, loses power, computers that were sending packets through Cumbersome can switch to other connected computers. It usually works quickly and reliably, although the techniques used internally by the Internet computers get a bit hairy at times.

Big computers are hooked together by high-speed communication lines: the Internet backbone. If you want to use the Internet from your business or your house, you must connect to one of the big computers first. Companies that own the big computers — Internet service providers (ISPs) — get to charge you for the privilege of getting on the Internet through their big computers. The ISPs, in turn, pay the companies that own the cables (and satellites) that comprise the Internet backbone for a slice of the backbone.

If all this sounds like a big-fish-eats-smaller-fish-eats-smaller-fish arrangement, that’s quite a good analogy.

It’s backbone-breaking work, but somebody’s gotta do it.