A few minutes later, Mr. Kahn gave in and started his own account: @mileskahn. Mr. Hodgman linked to Mr. Kahn’s page and, almost instantly, hundreds of the more than 25,000 of Mr. Hodgman’s fans who subscribe to his Twitter updates started following @mileskahn.

“Oh dear. What have I gotten myself into. Hooooodgmaaaaaan!” Mr. Kahn blogged, two minutes after signing up. “How will twitter change my life? And how can I exact revenge on John Hodgman?”

On its surface, Twitter seems like the consummate procrastination tool for a new generation of narcissists. Signing up is easy: Users enter a username, password and email address and are issued a blog page, to which they submit updates about daily routines, musings and activities. Each entry is limited to 140 characters, including spaces, punctuation and room for links. You can “follow” other updates from friends, coworkers and corporate accounts, and their “tweets” will be displayed in a simple layout on the home page. Whether they’re “riding the N to work,” “gossiping with the boss at the Spotted Pig” or “reading the latest issue of The New York Observer”—it’ll all be there on Twitter. The blog is public by default, so anybody can check individual updates unless a user makes them private; then only approved “followers” can see them. Twitter works on desktop computers’ Web browsers, but busy New Yorkers can also text-message updates to their account or download applications onto their iPhones or BlackBerrys to keep their followers up to date, on the go.

Although Twitter was popular among the early-adopter geek set in 2007, it didn’t become achieve juggernaut status until last year. The site’s administrators do not release official numbers of users, but TwitDir, an independent online tracking service, estimated that there are more than three million. According to HubSpot, an Internet marketing company, 70 percent of Twitter users joined last year, and 5,000 to 10,000 new accounts are added every day.

Twitter is tiny compared to social networking behemoths like Facebook (which has more than 60 million active users and an average of 250,000 new registrations per day, according to company stats, not to mention offering a Twitterish status-update feature as part of its service), but for now, at least, it is the hot thing.

So who is Twittering? Everyone from pop stars like Britney Spears (@britneyspears: “I love Japan! I think all the tiny cars are so cute!”) to sports figures like biker Lance Armstrong (@lancearmstrong: “Hammered 80 miles today”) and the self-proclaimed “very quotatious” Shaquille O’Neal (@the_real_shaq: “Twitter me this, twitter me that. Hello to all my twittereans, This is the shaq Love u guys”). Diablo Cody, the Juno screenwriter and former stripper, will be live-Twittering the premiere of her new Showtime sitcom The United States of Tara on Jan. 18 at the account @DiabloOnTara. “It’ll be like Pop-Up Video only even lamer and more meta,” she wrote in a statement.

And of course media people have accounts, from airy Web-lebrities like Julia Allison (@juliaallison: “I am listening to a Techno Remix of Titanic’s “My Heart Will Go On”) to The New Yorker’s music writer Sasha Frere-Jones (@sashafrerejones: “I want Britt Daniel to mix all rock records”). Barack Obama’s new-media team touted Twitter as a powerful tool during his presidential campaign. Hillary Clinton is on there, too. So is Al Gore. News services including The New York Times and CNN have joined, updating with their latest headlines. There is an account called @themediaisdying, run by an anonymous publicist who announces the latest insider news on media layoffs and magazine shutterings. And for those who still have a lunch break, there’s a user-generated Shake Shack account which continually updates how long the line is at Danny Meyer’s popular Madison Square Park fast food joint.

MOST PEOPLE who aren’t Twitter users don’t get it. They are already bored to tears reading Facebook status messages about their friends “needing coffee” or announcing that “it’s snowing!” I can look out the window too, pal. Isn’t there already enough white noise on the Internet? Can we say anything meaningful in 140 characters? Why would I risk my privacy and announce where I am at all hours? Isn’t this just another popularity contest? (The number of people you follow, along with the number of people who follow you, are prominently displayed at the top of your blog page.)

SURELY, some Twitter users are on there solely to get their ego fix. There’s also lots of publicists on there trying to shill their company’s products (cheers, @Starbucks!). But once you start following the right people, Twitter can be useful, converging some of the best aspects of the Internet into a customized message board, news service, gossip blog and email client all in one.

According to Twitter’s Web site, the first prototype of the microblogging platform was built in two weeks in March 2006, as a side project of Jack Dorsey, a St. Louis native, who attended New York University and worked in Manhattan as a software engineer before moving to California. He built Twitter based on a simple interest: What were his friends doing? What are they seeing, reading, listening to? Facebook and instant-messaging status updates provided some insight, but most people aren’t specific enough. Blog entries can be too long and time consuming. What about something simple and easy to manage?

Mr. Dorsey developed Twitter alongside co-founders Evan Williams (who launched the Blogger blogging platform) and Silicon Valley entrepreneur Biz Stone, and introduced the site publicly in August 2006. In May 2007, Twitter Incorporated was founded.

Facebook attempted to buy Twitter last November for $500 million in stock. Twitter declines, and still hasn’t come up with a business model that satisfies the technorati; the site has very little advertising.

Many describe the Twitter experience as an online water cooler (or happy hour, depending on the kind of people you follow) where friends and coworkers can check in on each other during the day and find out what everyone is doing or interested in. It’s also kind of like a personal RSS feed, updating you on acquaintances’ lives in short headlines. If a friend “tweets” that he’s at the Guggenheim, you can tell him to check out your favorite Kandinsky painting on the second floor. If one of the users you follow tweets that they need a Thai restaurant recommendation, you can respond to them with a “Direct Message” (kind of like an email service on Twitter) or just put an “@” symbol before their account name in an update, and the response will be public. You can also check out what his followers recom mended, and try a new place next time you’re in the mood for pad see ew.

Twitter also works as a genuine news aggregator. Lots of tech blogs have been hyping Twitter’s potential since its inception. It became a source for emergency coordination and disaster relief during the San Diego fires in 2007. In November, on-the-ground reports of Mumbai terror attacks also put the idea in motion. CNN reported that an estimated 80 messages, or “tweets,” were being sent to Twitter.com via SMS every five seconds, providing eyewitness accounts and updates. In some cases, Twitterers were able to be on the scene long before TV and newspaper reporters could get there.

Sure, Twitter has its problems. Sometimes the site crashes from too much traffic and you can’t update your blog. Sometimes it feels like a creepy, text-based GPS friends-tracker (lots of people download a LoJack-like iPhone application, posting the device’s global coordinates in real time on their Twitter page). And hackers are on the attack. On Jan. 5, a bunch of high-profile accounts, including CNN’s Rick Sanchez, were invaded. Britney Spears’s had this update: “HI Yall! Brit Brit here, just wanted to update you all on the size of my vagina. Its about 4 feet wide with razor sharp teeth.” It was later removed.

At its worst, Twitter is an addictive annoyance that could just end up being another fad in the ever-changing tech landscape. But at its best, Twitter provides a vast array of often informative, sometimes hilarious, updates from the Web into one place. And crafting tweets is a daily practice in pithy precision. My account is @gillianmae. Come follow me.

greagan@observer.com