By Scott Rosenberg
Pop quiz: What's wrong with these items?
(1) Afghani pizza! Call 894-73210 for free delivery!
(2) HairNet -- for all your online grooming needs! E-mail infohairnet.com for details.
A century into the telephone age, most of our eyes are well trained to read phone numbers. Add an extra digit and we know something's off.
E-mail is newer, and its syntax hasn't yet entered the general knowledge pool. To anyone who works with Internet e-mail regularly, though, the address above will set off an alarm bell as quickly as any eight-digit phone number: It's missing its @.
This may seem trivial, and it is -- unless you actually want your e-mail to reach its destination. That @ sign is essential for the computers on the Internet to route your mail. You may be able to tell from context that it belongs right between the "info" and the "hairnet," but the machines are not that smart.
As the Internet increasingly becomes a part of daily life, e-mail addresses are entering everyday parlance. And too often, they're arriving garbled. That's hardly surprising, since the Net wasn't originally designed as a mass-market medium. Now that it has become one, here's a quick guide to its addressing system -- information as basic, and as useful, as how to format a business letter or how to dial a telepone.
All e-mail addresses consist of two elements separated by the @ sign -- for instance, email@example.com. Everything preceding the @ specifies the individual to whom you're sending the mail; everything after it specifies the "domain" or computer subsystem where that individual is located on the Internet.
In some ways, the system functions like the telephone system's area codes. Just as the same phone number can connect you to different people if you change the area code, the same individual name refers to different people in different domains -- firstname.lastname@example.org ought to be Bill Clinton, whereas email@example.com is someone else entirely.
The @ sign often vanishes by accident when e-mail addresses are printed in newspapers and magazines because many older computer systems -- including those used by the Associated Press -- reserve the symbol as a special control code, meaning it can't be used in copy. If you see an e-mail address in print that's missing its @, you'll need to figure out where the symbol belongs before you can use the address.
Some large mail systems connected to the Internet, like the one used by Compuserve, clumsily use numbers to identify individual addressees (a Compuserve address looks like "firstname.lastname@example.org" ). Fortunately, any good e-mail program, like the widely used Eudora, will let you assign nicknames to frequently used addresses -- so that if you regularly write someone on Compuserve, you don't need to type the numbers in more than once.
When Internet-connected computers talk to each other, they, too, use numbers known as IP addresses -- sequences of four numbers below 256 separated by periods, like "18.104.22.168" (that's an IP address for the Well, the popular Bay-Area based conferencing system). The Net's meteoric growth rate means that these numbers are going to run out sometime in the next decade, but the committees responsible for such things have already begun planning a new numerical system to ease the problem, known as "IP-NG" for "next generation."
It would be tedious and annoying to have to remember and type an IP address each time you wanted to find or send something over the Net. That's where the domain naming system comes in. "Whitehouse.gov," "sfexaminer.com," and the other domain names that have become such a common sight in e-mail and Web-site addresses are pointers to numerical IP addresses. IP addresses are built to fit a microprocessor's 16-bit brain; domain names work more naturally with the human brain.
U.S. domains fall into classes like ".com" (commercial), ".gov" (government), ".edu" (educational), ".net" (network resources), ".mil" (military), and so forth. Occasionally you'll see references to a different, geographically-based naming scheme -- "well.sf.ca.us" rather than "well.com" -- but its use seems to be fading. Meanwhile, outside of the U.S., domains are typically organized by "country codes" -- ".uk," for United Kingdom, ".jp" for Japan, and so on.
Many people who remain unfamiliar with e-mail conventions, or who suffer from a vaguer sense of technological overload, still find the medium awkward, impersonal or difficult to master. Here, once more, the telephone comparison is illuminating.
After all, what could be more impersonal or tiresome than having to memorize or jot down a 7-digit number for each of your friends and colleagues? E-mail has its quirks -- don't forget those @ signs -- but at least it lets us use names that mean something.
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