How did we ever live without the iPod?

At the moment when my 10-year-old thought her Huey was lost, a look of panic crossed her face that I immediately understood. Huey, soon found under the car seat, is not a pet mouse or a little brother but her Nano – a slim permutation of the iPod digital music player that in the past five years has sped from inception to ubiquity.

It wasn't just that she knew that the device, a gift, would be costly to replace. Among an iPod owner's first acts is to assign to his palm-size pal a moniker more friendly than the one given by default with registration, a your-name-here possessive.

After that, it's love.

Intuitive to use, in true Apple fashion (sweet, thumb-able wheel!), an iPod also quickly makes itself indispensable, standing ready like a tiny concierge with vast personal playlists, easily uploaded and summarily sorted into soundtracks for every mood.

Yes, it has detractors. An iPod can be isolating if its white-earbuds-wearing user allows it to be. Cranked too loud it can hurt the ears. Like any material object it can be fetishized to unhealthy heights.

But as cool tool and technological Meisterwerk, iPod deserves a biography on its fifth birthday. It gets a deep and richly written one in Steven Levy's The Perfect Thing: How the iPod Shuffles Commerce, Culture, and Coolness.

Levy is a fan without reservation. He is, for example, so taken with the iPod's shuffle function – the device jumbles the listening library and presents songs in random order – that he persuaded the publisher to let him mimic it.

Chapters appear as modular, stand-alone treatments of different facets of the phenomenon – "Origin," "Download," "Identity," and so on – and a reader might pick up any of four shuffled versions of the book. (The approach mostly works, even if it calls for the occasional brief reintroduction of a point already made.)

His treatment of shuffle also highlights Levy's remarkable depth of access. Recounting one of many private encounters with unrelenting visionary Steve Jobs, Apple's chief, the author describes a heady chat about the "randomizing algorithm" of shuffle.

Levy has noticed what he thinks is a disproportionate representation of Steely Dan songs in the playlist his iPod concocts from his deep, varied collection. On the spot, Jobs has an aide call Apple headquarters in Cupertino, Calif., and the three of them parse the cryptography involved in the selection process.

Levy, a senior editor and chief technology writer for Newsweek, handily lays out the landscape from which iPod – deliverer of "portable alternative reality" – dramatically emerged. (And keeps emerging. After a sales surge in 2004, Apple sold 42 million iPods by the end of 2005 and blew past 50 million units soon after.)

He breezily covers the history of transistor technology and the sweeping evolution of the "personal audio experience" as both technology and business battleground, from the crude forerunners of Sony's Walkman to the advent of the MP3 format and its early players to the daggers-out days of Napster and the file-sharing firms that followed.

The rise of legal online music store iTunes is cast as only a matter of time. As Jobs told Levy in 2004: "The Internet was built to deliver music." Jobs's triumph: leveraging Apple's smallness in the world of personal computing to win the race and revolutionize the method and the machinery.

Levy laces the book with telling company lore: The English judge who heard a case involving a Beatles lawsuit over Apple's entry into the music business (the name Apple is also a Beatles trademark) began proceedings by confessing that he was an avid iPod user.

At a late-'90s event unveiling the iMac, Jobs – though well-versed in intellectual-property law – boldly insisted on using a cartoon video clip from "The Jetsons" even when he learned at the last minute that permission had not yet been formally granted. (The paperwork went though after the fact.)

Levy assigns Jobs a few warts, if hesitantly. Apple workers are described as being frustrated at times by their boss's legendary stubbornness and stung by his occasionally dismissive critiques. And Levy describes an exchange Jobs had with Casey Neistat, whose much-downloaded film "The iPod's Dirty Secret," detailed Mr. Neistat's 2003 experience with Apple support staff. When his battery died prematurely, Neistat was told that for what a new battery would cost, he might as well buy a new iPod.

Apple's replacement policy was soon rewritten (the company said a change had already been planned). But Neistat later wrote to Jobs asking whether he thought the initial policy had been a mistake. "Nope," Jobs wrote back in full, according to Levy. "I don't think Apple made a mistake. Steve."

Jobs gives little ground. Asked by Levy how he finds the viewing experience on the video iPod's tiny screen, Jobs replies "fine," faint praise, Levy points out, from someone prone to hurl such adjectives as "insanely great."

But both Apple and Jobs, Levy persuades, continue to emit brilliance, navigating the rocks of digital rights management, morphing the product, winning over fans from rock stars to college kids to preteen girls.

"When companies ... think of improvements to their products, they figure out how to put more capacity in them, extend battery life, make more colors, add FM radios," Levy writes. "But they don't make iPods, and people know it."

• Clay Collins, a Monitor staff writer, lives in a four-iPod household.