Shanda Edstrom can't stop herself.

Every day — pretty much no matter where she is — she has just gotta go to MySpace.

Her friends are there. Her former high school classmates hang out there. Heck, these days it seems like every teen and twentysomething in the U.S. is there.

"I'm on it every day for, like, two hours at a minimum," says Edstrom, 18, of Clackamas, Ore., who works at a Kinko's in Portland. "It's just crazy."

Forget the mall. Forget the movies. Forget school. Forget even AOL. If you're a teen in America today, the place to be is the social networking site MySpace, which has virtually exploded in the past few months.

Google just named it the top gainer for 2005, and in only two years, MySpace has shot from zero to 47.3 million members, say founders Chris DeWolfe, 39, and Tom Anderson, 29. They launched MySpace in January 2004. In July, Rupert Murdoch's News Corp. bought MySpace for $580 million, but DeWolfe and Anderson still are chief executive officer and president.

"This site caught us by surprise," says Pete Blackshaw of market researcher Intelliseek. "I honestly was flabbergasted by the numbers."

For those who didn't grow up with the Internet, it might seem strange to think of a mere Web site as an actual place.

But for people like Edstrom and Michael Edwards, a high school senior from San Diego, who can't remember when there was no Internet, cyberspace is a real place, even if the entry gates come in the form of a PC.

And at least these days, one's MySpace page is not just a home in that place; it's actually who they are online.

"Your page is like your personality," Edwards says.

Judging from his, Edwards, 17, is a young hip guy who is as much into music as he is into his family (two of his 10 pictures are family shots). He likes open-minded and cool people but not nerds and liars. And he really likes Hilary Duff — he plays a song "Ode to Hilary Duff" on his MySpace page.

So just what do people do on MySpace?

They redecorate their pages, adding new pictures (often sexy). They spruce up their surroundings with new colors, backgrounds and images. Serious MySpace users brag about knowing a thing or two about HTML coding. They write poetry and put up their own art. They write about themselves.

They play music for friends and post music videos. Some are from well-known artists. Many are from virtual unknowns who go to MySpace just to promote their music.

MySpace is fast becoming an avenue for musicians to reach out to fans and become stars.

Wired magazine recently featured the band Hawthorne Heights, which became a success after signing up with My Space. And MySpace recently launched its own record label, debuting with Hollywood Undead, a rap band that launched on MySpace in June and now has developed a MySpace following of 111,000 "friends" — people who have joined their network.

Edwards is so into MySpace that he and fellow high school senior Joyce Pace, 18, recorded an ode to MySpace — rewritten lyrics to the Black Eyed Peas' song "My Humps" — and posted it on the site.

"Whatchu gonna do with all them friends, all them friends that's on your page," the song begins. "I'm m-m-m-m-make them comment, make them comment on MySpace, MySpace ... OMG it's MySpace, MySpace."

Then there's the purely social part of it: Instead of the antiquated teen ritual of talking on the phone for hours, MySpace members spend hour upon hour sending each other instant messages and short messages called bulletins.

But mostly, what they do is cruise — big time, wandering from page to page in a tangled network that allows people to create links to each other's pages by naming each other a "friend." The process of finding new friends — often strangers — is called "friending." And for many teens, it's the glue that makes them stick with MySpace.

"Teens are narcissistic and exhibitionist," says Anastasia Goodstein, who publishes the online news and commentary site Ypulse, about Generation Y. "For teens, especially, who are going through this stage where they're constantly looking for that affirmation and validation and response for everything they are, it's just addictive."