Zuckerberg had been hard at work on Facebook for five years by the time he hit age 25. In that year — 2009 — the company turned cash positive for the first time and hit 300 million users. He was excited at the time, but said it was just the start, writing on Facebook that "the way we think about this is that we're just getting started on our goal of connecting everyone."

The next year, he was named "Person of the Year" by Time magazine.