Whenever Jason Berkowitz listens to "You're the Best" on his iPod, he recalls that 1984 summer vacation in Fort Lauderdale and seeing "The Karate Kid" for the first time. ("I thought it was the best song ever. I still kinda do and I don't care what people say," says the 29-year-old.) Whenever he listens to Zero 7's song "Destiny," which he first heard at London's Heathrow Airport four years ago, he thinks about meeting his wife, Bethany. Before you even get to the surface of the iPod, you encounter what could be called its aura. The commercial version of an aura is a brand, and while Apple may be a niche player in the computer market, the fanatical brand loyalty of its customers is legendary. A journalist, Leander Kahney, has even written a book about it, ''The Cult of Mac,'' to be published in the spring. As he points out, that base has supported the company with a faith in its will to innovate -- even during stretches when it hasn't. Apple is also a giant in the world of industrial design.

The candy-colored look of the iMac has been so widely copied that it's now a visual cliché. But the iPod is making an even bigger impression. Bruce Claxton, who is the current president of the Industrial Designers Society of America and a senior designer at Motorola, calls the device emblematic of a shift toward products that are ''an antidote to the hyper lifestyle,'' which might be symbolized by hand-held devices that bristle with buttons and controls that seem to promise a million functions if you only had time to figure them all out. ''People are seeking out products that are not just simple to use but a joy to use.'' Moby, the recording artist, has been a high-profile iPod booster since the product's debut. ''The kind of insidious revolutionary quality of the iPod,'' he says, ''is that it's so elegant and logical, it becomes part of your life so quickly that you can't remember what it was like beforehand.'' Tuesday nights, Andrew Andrew's iParty happens at a club called APT on the spooky, far western end of 13th Street.

They show up at about 10 in matching sweat jackets and sneakers, matching eyeglasses, matching haircuts. They connect their matching iPods to a modest Gemini mixer that they've fitted with a white front panel to make it look more iPodish. The iPods sit on either side of the mixer, on their backs, so they look like tiny turntables. Andrew Andrew changes into matching lab coats and ties. They hand out long song lists to patrons, who take a number and, when called, are invited up to program a seven-minute set. At around midnight, the actor Elijah Wood (Frodo) has turned up and is permitted to plug his own iPod into Andrew Andrew's system. His set includes a Squarepusher song. Between songs at APT, each Andrew analyzed the iPod. In talking about how hard it was, at first, to believe that so much music could be stuffed into such a tiny object, they came back to the scroll wheel as the key to the product's initial seductiveness. ''It really bridged the gap,'' Andrew observed, ''between fantasy and reality.''  The thing about the iPod is, it's what you bring to it."It becomes an extension of you. It's like a window to your soul," says Jason Berkowitz of his iPod.

When he hears "Destiny," he thinks of meeting his wife. (By Lucian Perkins -- The Washington Post) "If a song represents a memory in your head, then you listen to your life's memories -- faster than a mixed CD, definitely faster than a mixed tape -- as you listen to your iPod," says the affable, fast-talking Berkowitz, a project manager for a software company, as he sits in his downtown Washington office. "It becomes an extension of you," he says. "It's like a window to your soul." Everywhere, at all times, it's with you, this personal narrative of who you are and what you've been. While shopping for Cocoa Puffs at Harris Teeter. While dozing off on the MARC train. While doing leg extensions at Gold's Gym. It takes you back to that first dance ("When Will I Be Loved" by Linda Ronstadt) and last dance ("I'm in You" by Peter Frampton) at your senior prom; that birthday party where you sang like Rick James so loudly ("Superfreak! Superfreak!") that the neighbors almost called the cops; that Whitney Houston breakup anthem that reminds you of you-know-who over and over again. It's an obsession, an addiction, a love affair, really, between a man and a machine.

To the iPodders around the world, the irresistible, indispensable, irreplaceable iPod is a personal memory bank. "The iPod is a very powerful identity technology," says Sherry Turkle, director of the Initiative on Technology and the Self at MIT, where she teaches the psychology of the relationship between people and machines. The iPod, to be sure, isn't the only digital music player around, but it's without a doubt the most popular. With nearly 22 million sold, three-quarters of the U.S. market, "the iPod is just one more technology that uses the computer as the second self -- a reflection of who we are as people, a way of seeing ourselves in the mirror of the machine," she says. Fatima Ayub, wearing a white chiffon hijab that matches her iPod's white earphones, is walking briskly on R Street in Northwest Washington on her way to work. You'd hardly ever see her, she says, without her 15-gigabyte iPod, which has more than 1,300 songs on it.