ATLANTA - Pamela Elder, a junior at Georgia State University, got hooked when she found some old high school classmates. Next she used the online yearbook of yearbooks to track down people she hadn't seen since grade school.
No wonder the Facebook is an Internet sensation at campuses across the nation. Constantly updated by its 2.8 million registered users at more than 800 colleges and universities, the Facebook takes the local malt shop social nexus of the 1950s and makes it universal.
Started by three Harvard sophomores in February 2004 as an online directory to connect the higher education world through social networks, the Facebook now registers more than 5,800 new users a day.
"It becomes part of your daily routine. It's e-mail, the news, the weather, Facebook," said Lucas Garza, a senior from San Antonio studying aerospace engineering at the Georgia Institute of Technology.
Users of Facebook, http://www.thefacebook.com, can post a photo and a profile of themselves for free. The profiles include as little or as much information as the user desires, including basic biographies, lists of hobbies and interests, even home address and cell phone number.
Users control who can see their profiles - from only friends to all other users. Other users can then search the profiles for classmates, childhood acquaintances, people who share common interests.
When users identify someone on the site they'd like to meet, they can ask to be designated as a "friend," a characteristic of other social networking Web sites such as Friendster or LinkedIn.
Facebook friend requests can come from anyone on the site, including "some random drunk person you met at a party whose name you don't remember," said Garza, who has 143 "friends" on Facebook.
The site has become so ubiquitous among college students that they tell others to "facebook" them - to look them up on the site. Browsing it is known simply as "facebooking."
Site creators Mark Zuckerberg, Chris Hughes, and Dustin Moskovitz were roommates at Harvard when they designed Facebook so fellow Harvard students could get to know those living in other dorms. (The name comes from the real-life books of freshmen's faces, majors and hometowns that many colleges distribute to incoming students). The Web site proved so popular that the trio made it available to students at Columbia, Stanford and Yale within a month.
With Facebook's success, Moskovitz and Zuckerberg left Harvard to run it as a 10-person company out of Palo Alto, Calif. Moskovitz had been studying economics; Zuckerberg, computer science and psychology. Hughes, a history and literature major, is studying abroad in Paris.
"It's all at once a 'real-world' job and something surreal," Hughes said. "Instead of entering a company and working your way to the top, Mark has created something that has allowed him to start right off in the CEO seat."
Hughes said Facebook turns a profit, mostly from advertising. He refused to disclose the private company's earnings.
Besides corporate advertisers, Facebook users purchase "announcements" - ads that can be seen only by students from the same school. They range from campaign posters for student government positions to fliers about upcoming parties. They cost $9 to $15 apiece; the smaller the school, the cheaper the announcement.
Investments have boosted Facebook, too. Silicon Valley venture capital firm Accel Partners put in $13 million; PayPal founder Peter Thiel recently invested $500,000.
Users can register on the site only with a college e-mail address, which serves as verification that users are students. Once registered, the.edu address becomes a user ID.
More than 60 percent of the site's users log in daily during the school year, and about half log in daily over the summer, Hughes said.
Marketers who target students love the site, said Robin Raskin, a technology consultant whose three college-age children are all Facebook users.
"You've got this great, great group. You know their demographic, you know how much disposable income they have, you know what they spend it on, and now you've got them in one place," Raskin said. "It's great for anybody who wants to talk to the youth audience, and that is why investors have run to give Facebook some money."
Another result, however, is that students should be cautious about putting personal information on the site, said Raskin, a former editor of PC Magazine.
"You think you're safe because of this.edu address, but anybody can get in there who wants to," said Raskin, adding she knows corporate marketers who have "infiltrated" the site. Many alumni get.edu e-mail addresses from their alma maters, allowing them to get on Facebook.
Marcia Ammons, a Georgia State senior from Carrollton, Ga., swears by Facebook. She has two close friends on campus she first met on the Web site.
"It's hard to find people with similar interests on a big campus," Ammons said. "We're so spread out... you can put up party fliers in the Rec Center but half the people won't know about it because they won't see them."
Garza uses Facebook to find people in his classes to compare notes and homework, since a single class at Georgia Tech can have up to 500 students. During last year's presidential campaign, he used the site to find students with similar views. His profile included quotes from George Orwell and links to his personal Web site.
Students also meet on the site through groups, virtual clusters of users at the same school with a common interest. Ammons is a member of the "Wal-Mart Lovers" and "Rec Center Junkies" groups. Garza is in the "Anti-Leaf Blower Society" and "Ipodilicious," a collection of Ipod fans.
Entirely new social protocols have formed around Facebook. One surrounds confirming friend requests. For some, a person's friend count is a social barometer.
Says Hilton Gray, a 2003 graduate from the Massachusetts Institute of Technology and avid facebooker:
"I know a few people who like the attention of it all, so they try to rack up as many friends as possible."