There are even apps now devoted entirely to anonymity. Since last year, services like Secret, Whisper and Yik Yak have sprung up. They allow people to publish posts as they would on Facebook, but without their names attached.
Many find the anonymity appealing. "In one day, everyone at our school had downloaded Yik Yak," said one teenager who preferred his name not be used. He added, though, that the app has been banned from his school, mainly because of cyberbullying.
Among younger people, "part of it is avoiding the parents, but there's a larger recognition that what you post online could haunt you forever," Brookman said.
Clearly, whether it's on Secret or Google+, some people want a way to disassociate their identities from what they post.
Even Twitter, which likes to call itself the Internet's town hall, has been improving its direct messaging function, which lets people exchange messages privately.
And Facebook has linked up with Secret, in an odd pairing of public and private. The startup recently announced an integration with Facebook, to let users weave more posts from friends into their stream on Secret. Secret says the connections are made anonymously, and that it doesn't store people's real names.
Still, at the end of the day, Facebook and Google are businesses that provide free services monetized through data.
"The upshot for them is, they learn new things about how people use these privacy tools," said Fatemeh Khatibloo, an industry analyst at Forrester who studies digital privacy.
And depending on how people use them, that could help the companies provide better targeted ads. So, have a secret to tell? Facebook wants to help.