Johnny's sitting there, trying to decide how to sign his e-mail to Liz. He taps out "-Johnny."  He reconsiders, hits the Backspace key, and taps a few more keys. There it is: "Love, Johnny." He pauses, the cursor hovering over the Send button. There's still time to change the signature line, but he's certain now. He clicks.

Normally, Johnny wouldn't think twice about what happens next to his message, but he's in a rather sentimental mood. With a modest background in computer science, he knows the message will cross nearly 3,000 miles of networked wires from his apartment in Los Angeles to Liz's in New York.  

To make the trip, L will have to lose its name, because like creditors and the DMV, computers can only identify with numbers. So the computer issues L eight binary digits, or bits--the 0s and 1s that, in clusters of eight, make one byte. L translates to "01001100" in binary. In a sense, that string of digits acts as L's identification tag.
 
The hard drive on Johnny's computer contains billions and billions of bytes just like L. Each letter, each comma, each period of his message also amounts to a byte and has a unique binary ID. With all these bytes properly identified and lined up neatly, it's impossible to tell where one byte ends and another begins, really. The letters and commas and periods blend together until they look like this: 0100110010101110101011010010011101, and so on.

It is the e-mail application's job to prepare L and the other bytes for the big send-off. This hefty application works like a factory, padding the message with extra information in the form of more bytes. These extra bytes are sent ahead of the pack, embedded in the same header that lists subject, sender and date, but invisible to the user. The header's job is to convey special instructions for handling everything that follows. It's like sending a representative from a construction firm ahead of a shipment to explain to the people on the receiving end how to unpack the freight trucks and reassemble the contents into a house.

With the header ready, the e-mail application ushers L and the other bytes down to the network card, where they find their seats, as it were, on one of a caravan of buses--the packets that will make it more efficient to send information across a network. These packets come in various sizes, but many hold up to 4,000 bytes. That seems like a lot of characters for one message, but actually a substantial portion of those bytes are part of the header.

L's packet gets in line near the cable that connects Johnny's computer to the Internet and ultimately to Liz's computer. In a sense, though, L is all dressed up with nowhere to go, because the packets won't actually be traveling. The computer will read the information on the identification tags and, in a kind of Morse code, call out the 0s and 1s across the network.  But where Morse code relies on long and short sounds to send information, binary code relies simply on turning on or off an electromagnetic current. A 1 means on. A 0 means off. Both sending and receiving computers synchronize their clocks, and with perfect rhythm Johnny's computer will switch the transmission either on or off.

The packet of bytes in front of L's team moves forward, and all its passengers have their identification tags read and relayed down the line--on, off, on, off. When L's packet comes to the front of the line, the computer suddenly stops transmitting.

But that's normal. Networks operate a bit like streets--if the light at an intersection stays green too long, cross traffic gets clogged. Similarly, if all the packets went in an unbroken row, the data line would be tied up, preventing other computers from sending other heartfelt messages. L's packet is simply waiting for the light to turn green. And since the packets are traveling separately, the header will arrive first and tell Liz's computer, "Hey, there are 100 packages en route, so don't try reassembling all this stuff until you have all of them."

Finally, L's packet has its turn and L's ID is read off: "01001100." The computer measures out the beats: off, on, off, off, on, on, off, off.

At each hub along the information superhighway, a computer receives the signal and records it as bytes in a packet. It signals the next hub and so on down the line. When a line is temporarily busy, the computer hub holds the packet for a short layover. The signal pattern for L's packet travels hundreds of miles at a time--Los Angeles to Houston, Houston to Denver, Denver to Detroit, and so on until it reaches New York.

Eventually, the signal arrives at its destination. The network card on Liz's computer has been monitoring the line and begins recording--current or no current, 1 or 0--keeping the same rhythm as the sender. Gradually the network card has a long string to work with. It snips every eighth bit and reads the subsequent string as a byte. After reading the header for instructions, it sends all those bytes to Liz's e-mail application, which transforms the digits back into letters. At some point, the application comes across that familiar ID, "01001100," and shoots an "L" onto her screen.  

Of course, all this happens in a matter of seconds. Johnny and Liz have already traded numerous e-mail messages today. This time, Liz sees the "Love, Johnny," panics, and sends a quick reply. Her message takes the same fantastic route, all the characters changing to bits and then pulsing across the Web to Johnny's computer. Unfortunately for Johnny, preceding Liz's name is not the "01001100" beginning the L word. Instead, her message reads, "I think we're better off as friends. -Liz."