Another photo blinks onto the computer screen of University of Pittsburgh senior Brian Kelly -- the latest image among scores coming from students suddenly asking to be part of his "social network."

	John Heller, Post-Gazette Ashleigh Kuhn, 20, has her personalized home page on display on her computer screen in her Oakland apartment. Click photo for larger image.

The accompanying description this time belongs to a male classmate, someone Kelly remembers from earlier years. Like the others, the sender is putting his popularity to the test using the newest rage on college campuses -- a Web site that now claims addicts from Berkeley to Bucknell to the Big 10.

Kelly weighs the online request for all of two seconds, then uses a single keystroke to give his classmate the thumbs up. In the parlance of The Facebook, Kelly has just "friended" him.

"He's a good kid. He was in my freshman studies class. I'm going to confirm it," Kelly said as he tapped the keyboard the other day. "Now he's my friend, and I'm his."

And just like that, another of the nearly 1 million registered users of www.thefacebook.com managed to expand his social network by one.

Created by a Harvard University student, The Facebook is a virtual community of sorts letting students seek out peers with similar interests on their campus and others. Devotees describe its allure in various ways, from a useful introduction service, to an outlet for creativity and vanity, to simply an irresistible database that clues them in on the faces they see on campus every day.

Using their school-issued e-mail address and a password, students registered with The Facebook post photos of themselves along with personal information of their choosing, such as classes, a favorite book or even their cell phone number. A student then works on quickly accumulating friends, with each acquisition boosting a running tally that can be seen -- and perhaps envied -- by other users.

The site, created by Mark Zuckerberg, joins other online social directories such as Orkut and Friendster. But unlike some of those, The Facebook zeros in on college campuses and attributes much of its growth to students spreading the word.

Since Harvard students first began using it in February, the free, advertising-supported site has amassed more than 900,000 registered users on 256 campuses, including Pitt and Carnegie Mellon University. Daily hits on the site can top 40 million, and two-thirds of its users have logged on in the previous 24 hours, a sign of its draw, asserts Chris Hughes, another Harvard undergraduate and a spokesman for The Facebook.

"It's not a sort of site they use occasionally," he said. "It's something where you wake up in the morning, you check your e-mail, you check your Facebook and then you go to class."

Along with logging in to see if anyone new wants to "friend" them, students swap messages and join hundreds of virtual clubs that -- in some cases -- seem little more than political or satirical statements. At Pitt, along with ordinary sounding organizations, one can join "Hemingway's" (named for the off-campus bar and eatery, not the author), a group for suburban Philadelphia students, a group convinced they were wrongly denied Pitt basketball season tickets and one titled "WAWA," dedicated to appreciating the so-named convenience store chain headquartered in suburban Philadelphia.

It's the sort of group behavior sociologists could spend hours dissecting. Why, for instance, do people with seemingly endless chances to socialize face to face on campus flock to such a site? Is having half as many Facebook friends as your roommate any reason to think about moving back home?

"Every generation reinvents new ways of doing old things," said Deborah Abowitz, who chairs Bucknell University's sociology and anthropology department.

The Facebook's appeal strikes her as the cyber equivalent of what long has drawn students to urban coffee houses. And stockpiling friends seems "not just about social bonding, but keeping up with the Joneses."

Still, it also suggests a level of Internet comfort that older adults don't grasp. It plays out on her campus, where students often are more inclined to hash out a problem via e-mail than meet Abowitz face to face during office hours.

"They're on the Internet for the sake of being on the Internet, just like the way I sit in front of the television," agreed Daniel Santoro, an associate professor at the University of Pittsburgh's Johnstown campus who follows pop culture. "They grew up with instant messaging. They are so far ahead of us with this stuff."

Adding a Facebook friend to one's tally doesn't necessarily imply intent to spend time with that person. At Pitt, Kelly has amassed 345 friends in just over a month, in part through his contacts as undergraduate student government president and as a fraternity member. Many are close acquaintances at Pitt and other campuses served by The Facebook, but a few he has never met.

"Nobody really rejects friends unless you really hate somebody," he said. "It's all pretty non-committal."

The site even helped him reconnect with a hometown friend with whom he lost touch until a function built into The Facebook linked them to the same high school and identified her as attending Fairfield University in Connecticut.

"It's cool," he said. "We started messaging back and forth."

Sometimes the one-upsmanship gets out of hand. Ashleigh Kuhn, 20, of Penn Hills, another Pitt student, said a friend of Kelly's is so intent on surpassing his friend's total that "I think she actually sent invitations to people she didn't even know just to get her number up."

The site has security settings so users can limit who can access certain information. Some, clearly unafraid of the prospect for identity theft or stalkers, go so far as to include their home addresses when building their personal profile, students said.

Kuhn was a bit unsettled by two unsolicited online approaches from strangers, one from UCLA and another at Pitt who reached her via an AOL Instant Messenger account she posted on The Facebook site.

"It started to get me thinking that this was maybe getting a little out of hand," she said. "But it is fun."

Reviews by students have been glowing on many campuses, though at Harvard another group of students, saying Zuckerberg stole the idea for the site, filed a lawsuit in Boston, Hughes said.

A writer with the Yale Daily News described The Facebook as "so last year" to all but freshmen.

After all, what's the thrill once you've already "friended" half your campus?

"I'm not going to lie," said Hughes. "There is something to the novelty of The Facebook."

But he says data shows a degree of site loyalty. Ninety percent of users at new campuses log on daily. But even among the earliest campuses, the rate remains above 50 percent. Hughes said the site is hardly intended to be a substitute for interaction but rather enhances it by giving people insights about their peers.

The site debuted at Pitt only last month. Yet already, 6,410 accounts have been opened, said Hughes, a total equal to more than a third of the Oakland campus's undergraduate population. The average friend list there is 31, compared with 57 and Carnegie Mellon and 29 at Penn State University.

Hughes knows of some friend totals topping 700.

Many users take delight "poking" -- the electronic equivalent of a "Hey, what's up?" message, according to Kelly, but it contains no text other than informing individuals that they have been poked.

At Carnegie Mellon, freshman Julian Dunn, 18, of Harmony, said most of the 54 students on his dormitory floor have registered. He uses it mostly "when I'm on the Internet and I'm bored" and finds it particularly helpful in avoiding a form of campus awkwardness that plagued college students long before the Internet.

"Remembering people's names," he said. "You meet an awful lot of people.