But now Zuckerberg is more excited about messaging services than photos. That's because he feels there's a cap on how many photos people want to share with each other, but they always want to be communicating in some form.
"I'm so excited about messaging," Zuckerberg said on Facebook's Q2 earnings call Wednesday. "There are only so many photos you're going to want to share with friends - there's just a lot more people want to express."
Facebook is also letting up on mission to give people identities online. On the call, he was bullish on anonymous-friendly features.
"Things like anonymous login unlock different behaviors," he said. He explained that people are often more willing to share things and experiences when there isn't a name tied to it.
Facebook's job, Zuckerberg said, is to give people the tools they need to socialize and communicate- even if that means they don't match Facebook's founding principals.