It seems that all of a sudden, like, everyone is on Facebook.

The boss. The grandparents. Long-lost friends from high school.

Facebook attracted 25 million new users in the past month alone.

The social networking Web site that started off as an online hangout for college kids is exploding in popularity among grown-ups.

The real kind. The kind over 35.

Between June 2008 and January, the number of Facebook members ages 35 to 54 nearly quadrupled — and members older than 55 tripled, according to iStrategyLabs, a digital marketing agency.

"It's like an avalanche that's just moving. If you're not on Facebook, your friends drag you in," said Robert Scoble, an expert in blogging and other online media. "It's in total expand-like-crazy mode."

Most Facebook users are younger than 35. But so many older people are now sending messages, sharing photos and "poking" at each other on Facebook that the portion of college-age users has dropped to 41 percent.

As Facebook's demographic matures, so do its uses.

The University of California at Davis is examining the "effectiveness of social media used by the higher education sector to communicate philanthropic news," according to a press release sent last month.

Translation: There are now enough old folks on Facebook that UC Davis will use it to ask them to kick down some cash.

Fundraising has become an accepted use for Facebook ever since Barack Obama's successful presidential campaign, which included groundbreaking uses of technology and social networking.

Now politicians and business people use it for professional networking.

But the Facebook fascination among grown-ups isn't all stodgy and purpose-driven. Many are hooked on the site for the same reason teenagers are: It's fun. You can look up old friends. Keep in touch with far-flung family members. Share pictures of the latest kegger or trip to Yosemite.

"Robust privacy settings make it easy to control who sees what content on your profile, so that colleagues at work see one version, and family members see another," Facebook spokeswoman Malorie Lucich said via e-mail.

RAPID GROWTH

Facebook was born in a Harvard dorm room in 2004 and was restricted to college students. A year later, high school students were allowed in. In 2006, Facebook got rid of its bouncers and began letting anyone into the club.

Over the next year, it grew from 12 million to 50 million users. Then it launched versions in Spanish, French and German. Today about 175 million people are on Facebook.

Steve Martarano joined around Christmastime and, at age 53, is part of Facebook's exploding demographic.

"All of a sudden I started getting requests from people," said Martarano, who works at the Sacramento office of the U.S. Fish and Wildlife Service. "You start looking at other people's friends and see people you know, and it just started to snowball."

Martarano gets on Facebook about once a day to post pictures or connect with his college alumni group. Something about Facebook reminds him of hanging out on America Online in the 1990s — in the early days of the Internet, when AOL was a pioneer in online chats.

"To me, Facebook has a little of a 'Here today, something else will happen tomorrow' quality about it," Martarano said.

Scoble, the technology expert, says eventually Facebook's popularity will slow — but not any time soon. And it remains cool with the college crowd.

"Having older people there doesn't affect your experience," Scoble said. "It's segregated. You have your friends and your whole experience there is based on who your friends are."

But with teenagers, college students, parents and grandparents all using Facebook these days, some overlap is inevitable.

Sacramento State sophomore Alyssa Bumgarner said her father recently asked her to help him set up a Facebook profile.

"At first I was like, 'I'm not gonna show you how to use it because I don't want you to see pictures of what college life is like,' " said Bumgarner, 19.

But then she realized her dad didn't just want to keep tabs on her. He actually had his own friends he wanted to reconnect with.

Bumgarner helped her father set up a Facebook page. Then came the moment of truth: He wanted to be her Facebook "friend," giving him access to many of her pictures and messages.

"I said, 'Here's the deal. I'll be friends with you if you promise you won't be mad if you see pictures of underage drinking,' " Bumgarner said she told her father.

He agreed. But before she accepted his friend request, Bumgarner deleted a few photos.

"I was like, 'I don't want Mom and Dad to see that,' " she said.

For parents, Facebook has opened a new avenue in communicating with college-age children. Shari Pesa of El Dorado Hills, Calif., joined recently to keep in touch with her son at school in Colorado.

"I would leave him messages and he would never call me back," she said.

Now they trade messages daily and she sees pictures of his weekend ski trips and the apartment he rented for next year.

"This way I feel like I'm with him every day," said Pesa, 42.

The combination of Facebook's addictive quality and its ease can have some drawbacks, however. The other day, Pesa said, she signed on and asked her son: "What are you doing?"

"He said, 'I'm studying for my midterm.' I said, 'Why are you on Facebook if you're studying for a midterm?' Now he's probably not so happy I'm on Facebook."