NEW YORK — Celebrity can be an interesting thing when distilled to no more than 140 characters.

As the micro-blogging platform Twitter.com has gone mainstream, an increasing number of celebrities have opened up accounts where they post messages — or "tweet" — about their daily lives. A tweet can't exceed 140 characters, but that limitation hasn't prevented the famous from revealing a new digital dimension of themselves.

There are star athletes (Shaquille O'Neal, Lance Armstrong), politicians (Sen. John McCain, President Obama before taking office) and stars ranging from the A-list to the D-list.

Some, like Britney Spears, usually post messages written by their supporting staff, simply announcing various events. Others, like Jimmy Fallon, are clearly promoting a new venture — in Fallon's case, his new late-night show on NBC.

But the real stars of Twitter are those who fully embrace the site's particular brand of conversational, detail-oriented banter. On the site, you can update your profile with as many tweets as you like. But you can also engage with others, responding to other tweets publicly.

This effectively means you can converse individually and with thousands simultaneously.

John Hodgman, a "Daily Show" correspondent and popular microblogger, said in an interview via Twitter: "What I really love is a) the harsh discipline of 140 char. b) the playfulness. It's a parlor game w/1 rule, inf. variations."

One of the most popular microbloggers is MC Hammer, the '90s rap star who has remade himself in the last decade as an Internet entrepreneur and co-founder of the video site www.DanceJam.com. He has more than 157,000 "followers" — users who receive his Twitter feed.

"It creates a new form of communication where we can actually see each other as people, humanizing the celebrity," said Hammer, who was born Stanley Burrell. "To me, it's a great human interaction that happens."

Hammer doesn't have a problem exposing his private life — he'll star in a reality series for A&E this spring — and he enjoys the lack of a filter between him and his fans.

"Most of the time you hear something from a celeb when there's a new project coming — 'My new movie is coming,' 'My new album is coming.' You only see them in those sound bites," said Hammer. "But with the Twitter platform, you're not only able to see what his or her life is like on a day-to-day basis ... but hour-to-hour, minute-to-minute."

Many stars already have their own blogs, but postings on blogs frequently are announcements or messages (think Lindsay Lohan expressing her support of Obama). With Twitter, there needs to be no purpose, no meaningfulness.

With Armstrong, one gets a sense of — among other things — his daily workout routine while he pursues his cycling comeback: "Heading out for a ride. Got 5 hours today. Just rollin' around."

Stephen Fry, the British comedian and most popular Twitter celeb with 281,000 followers, supplies a constant flow of wry observations. Recently, Fry even appeared to send messages while riding a donkey on a trip to Mexico: "You have to hand it to these beasts. Their sure-footedness is a miracle. Millions of years to perfect 4-hoofed precision."

Ashton Kutcher and his wife, Demi Moore (who posts under the name "mrskutcher"), are the most famous Twitter couple, and their tweets often reflect against each other. One from Kutcher: "this just in demi doesn't pee or poop or fart ... ever."

Julio Ojeda-Zapata, author of "Twitter Means Business," explains Twitter as a "virtual water cooler" where the famous must mingle just like everyone else.

"It's about getting down off your pedestal, coming down off the mountaintop, blending in with the masses and just trying to be another regular human being regardless of whether you have a product to pitch or whether you're a celebrity that has a movie to pimp," said Ojeda-Zapata.

One major impediment, though, is the number of fake accounts updated by impersonators. More than 72,000 are following a fake Stephen Colbert. There are dozens of plainly fictional accounts pretending to be characters like Darth Vader and Borat.

A spokeswoman for Tina Fey confirmed that the 89,000 people following Fey on Twitter are being duped. It's not a bad impression, though; a recent tweet read: "Amos probably didn't start out famous, but with cookies this good, it was a self-fulfilling prophecy."

Founded in 2006, Twitter Inc. is growing rapidly with more than 6 million users. It's yet to figure out ways to make money (though it has rebuffed takeover bids like Facebook's $500 million offer), so Twitter could be said to still be in its infancy — and thus still working out the kinks.

Biz Stone, a co-founder of Twitter, said in an e-mail: "Fake accounts can be inconvenient and impersonation is against our terms of service. Providing account verification might (be a) good opportunity to enhance the Twitter experience for everyone — that's something for us to think about."

Many celebrities (like Spears) come to Twitter simply to take ownership of their name, rather than let an impersonation continue.

When the comedian Michael Ian Black learned someone was twittering under his name, he felt: "I didn't want someone out there pretending they were me when it wasn't me because I do a good enough job of pretending that I'm me, myself."

The first thing he noticed was the great popularity of LeVar Burton ("Star Trek: the Next Generation"), which Black (jokingly) believed "was beyond the pale." He immediately started a mock contest — dubbed "LeWar" — with Burton, challenging him to see who could get the most followers.

"I would not have thought that LeVar Burton has legions of impassioned fans. I was very, very wrong," said Black. "If Twitter is any indication, they would die for him. 140 characters at a time, they would die for him."

The war was called after a few days — it had quickly become all-consuming for Black. He now posts a few a day. Others keep a frantic pace to quench their ever-thirsty followers. Hammer, for example, says he has screens around him everywhere and even has a device that loops back the most recent 100 tweets from those he's following.

One might wonder how anyone has the time, but Twitter does make it easy. You can text your tweets from your mobile phone.

"From my point of view," Black said, "... what it allows you to do is communicate very directly with people, but at the same time be able to keep them totally at arm's length — which I think is the goal of any celebrity, and believe me I used 'celebrity' referring to myself very advisably."