Facebook is about to celebrate its 10th birthday.
The pioneering social media company took in more than $2.5bn in revenue for the final quarter of 2013, and made a profit of $523m.
Conceived in a college dorm room, Facebook grew into a behemoth in large part because of young people who enthusiastically adopted it as a new means of communicating with their peers.
Now Facebook has nearly 950 million users worldwide. But fewer and fewer of them are teenagers.
DJ Saul of iStrategyLabs has studied Facebook's changing demographics.
"What we found is that in the last three years, there were three million fewer teenagers," he says.
Teenage Facebook users are defined as being between 13 and 17.
Saul says the 18-to-24 demographic is also moving away from Facebook.
"There is decline in both, specifically a 25 percent decline among addressable teenagers in Facebook advertising," Saul says.
To find out what is going on, we went right to the source: a bunch of cool kids hanging out after school in Santa Monica.
Blake Rose, a high school student and skateboarder, says Facebook has lost its allure.
"Like, this whole way where everybody can get a hold of you no matter what, and like they just know everything about your life, like ... I don't know. I don't like it anymore." Rose says.
"I like to have my own life and have the ability to choose who comments on it or not. I feel like with Facebook you lose that."
Increasingly, teens are communicating through different social-media platforms, says student Jordan Weinstein.
"I have a Twitter account, Instagram, Snapchat, Pinterest, all that cool stuff."
Teenager Maia Witkamp says Facebook started to lose its coolness factor when she realised her parents were following her every online move.
"It used to be kind of secret from your family. And now they're actually a part of it so they can see everything you're doing,” she said laughing.
"'Oh you're out drinking here'.'Uh, thanks Mom, yeah'."
In fact, the largest increase in Facebook users in recent years has been among people aged 55 and over.
Now that's, like, totally uncool.
"I think a huge part of it has to be attributed to the rise of parents and grandparents, aunts and uncles who are on the platform and commenting on photos that teens are posting," Saul says.
"And that's not what teens are looking for."
What teens are looking for is a parent-free zone online, says high school student Julia Njuliena.
"Older people wanna know what you are doing. They wanna like, like check what you are doing, you're not doing anything bad."
Many teens who still use Facebook are careful to keep the grown-ups out of the loop.
Teenager John Furth declares: "I'm not friends with my dad on Facebook although he does have an account."
Mom and Dad may have got Facebook accounts but, as always, they haven't got a clue.