ick Bruner's awakening to the power of the written word came by way of a throwaway line, typed one afternoon in the cerulean glow of his I.B.M. ThinkPad.

Mr. Bruner, a 37-year-old Manhattan marketing consultant, keeps a Web log, an online diary known as a blog. After coming in for some sporting abuse from a friend who told him blogging was a waste of time, Mr. Bruner wrote in his blog that the friend "was fat and runs like a girl," adding that he was sure the friend would not be offended "because he doesn't read blogs." With a push of a button, the comment was published on Mr. Bruner's site, http://www.bruner.net/blog/, and accessible to anyone with a computer.

A few days later, though, that friend's curiosity about blogs was awakened after all. He quickly found Mr. Bruner's site and was "deeply aggrieved," Mr. Bruner said. Their friendship barely survived the episode.

"It was a big wake-up call," Mr. Bruner said. "Sometimes it's good to have an editor."

Mr. Bruner's experience is typical of many who have waded into the thrilling and sometimes perilous world of blogging, a once marginal activity of Internet enthusiasts that has become squarely mainstream, with an estimated three million active blogs online, according to Nick Denton, the head of Gawker Media, a blog publisher.

While blogging journalists like Andrew Sullivan, Mickey Kaus and Eric Alterman get a lot of attention, a vast majority of bloggers are average citizens like Mr. Bruner, who draw from their personal experiences — and often the personal experiences of relatives, friends and colleagues — to create a kind of memoir in motion that details breakups and work and family issues with sometimes startling candor.

While personal blogs have been around for years, their proliferation has caused a wrinkle in the social fabric among people in their teens, 20's and early 30's. Inundated with bloggers, they are finding that every clique now has its own Matt Drudge, someone capable of instantly turning details of their lives into saucy Internet fare.

"It's like all your friends are reporters now," said Douglas Rushkoff, a blogger and author of "Media Virus" and other books about the impact of technology on society.

In the rush to publish, many bloggers are running headlong into some of the problems conventionally published memoirists know too well: hurt feelings, newly wary friends and relatives, and the occasional inflamed employer.

"All writing is a form of negotiation between the reader and writer over what constitutes responsibility," said David Weinberger, author of "Small Pieces Loosely Joined," a book about the Internet. "Because blogs are a new form, the negotiation can easily go awry."

Mr. Weinberger said the confessional nature of many blogs had "redrawn the line between what's private and public."

Heather Armstrong, a 27-year-old Web designer from Utah whose blog is at http://www.dooce.com/, might be the ultimate example of blogging gone awry. Her parents are devout Mormons, she said, but because they are also technophobes, she felt perfectly comfortable publishing an entry on her site in which she harshly criticized her Mormon upbringing.

Unfortunately for Ms. Armstrong, her brother in Seattle stumbled across her Web site that very day and alerted her parents to the entry. After that, Ms. Armstrong said, "all hell broke loose." "Next to my parents getting divorced 20 years ago," Ms. Armstrong said, "it was the worst thing that ever happened to my family. It was shocking for everyone."

Ms. Armstrong's run-in with the perils of self-publishing did not end there. She also wrote about her job and her co-workers in her blog, often hyperbolically.

When her bosses were alerted that Ms. Armstrong was writing about her office life, they fired her, she said. She is now much more careful about what she publishes in her blog, and she had a word of caution for bloggers who write furtively about others. "If you're publishing under your own name, they'll find out," she said. "I was extremely naïve."

Being found out is no deterrent for 18-year-old Trisha Allen, a blogger from Kentucky. She has been blogging for roughly a month, and spends most of her time reporting candidly on her friends and on her relationship with her boyfriend.

A recent entry reveals that the couple are not quite ready for children — though "we have had two scares" — and that Ms. Allen's preferred form of birth control is the pill, even though, she wrote, "I am starting to hate it, because it has screwed up my menstrual cycle wickedly."

"There's not a lot I won't put on there," Ms. Allen said by telephone. Ms. Allen said her mother was aware she keeps an online journal, but does not know how to find it, and added that she relied on a doctrine of security by obscurity, hoping that in the vast universe of personal Web sites known as the blogosphere, she will be able to preserve her anonymity behind all those other blogs.

Ms. Allen said her motivation for posting personal details was simple: "I love to be the center of attention."

Indeed, for many bloggers being noticed seems to be the point. John M. Grohol, a psychologist in the Boston area who has written about bloggers, said they often offered intimate details of their lives as a ploy to build readership.

"It's like, `How do I get people to read this?' " he said. "Then you want them to keep reading it. It becomes a snowball rolling downhill that becomes very rewarding for the blogger because they're getting feedback from their friends and from random folks."

Deirdre Clemente, a blogger from Brooklyn who is now a a student at the Fashion Institute of Technology in Manhattan, frequently uses her relationships as fodder for her blog, http://www.deirdreclemente.com/.

That became an issue for a recent boyfriend of hers, a 34-year-old Manhattan hedge-fund manager who feared that having his name in the blog could compromise his business relationships.

During his eight-month stint as a nameless regular on Ms. Clemente's site, he said, "it was an odd feeling that there was a camera on me." Friends and relatives who knew about the site followed his relationship online, he said.

"On occasion my mother would send me an e-mail saying, `How was the play?' or, `Sounds like you had a nice weekend away,' " he said.

But as a literary trope, the boyfriend worked well. Ms. Clemente said she frequently received e-mail messages from strangers who followed the ups and downs of their relationship on her blog.

When the relationship ended, she said, "I had totally random people e-mailing me saying they were sad we broke up." She described the experience as "totally weird," but added, "As a writer, having anyone read your stuff is a compliment."

With so many self-publishing reporters out there, some say they feel a need to watch themselves, for fear that casual comments made to friends might make tomorrow morning's entry.

The proliferation of personal bloggers has led to a new social anxiety: the fear of getting blogged.

"It's personal etiquette meets journalistic rules," Mr. Denton, the blog publisher, said. "If you have a friend who's a blogger you have to say, `This is not for blogging.' It's the blogging equivalent of `This is off the record.' "

Jonathan Van Gieson, a 29-year-old theatrical producer from Brooklyn who sometimes writes about friends on his site, http://www.jonathanvangieson.com/, said he gave his friends pseudonyms "to toe the line between simple harmless betrayal of trust and nasty actionable libel." Before starting his blog, Mr. Van Gieson said he drew a comic strip based on his friends for his college newspaper, and in describing their predicament he summed up the current lot of many in the age of blogging.

"My close friends are used to having their lives plundered," he said.