Facebook reached 1 billion users in September 2012, but, for reasons that went unexplained, it didn't announce the milestone until October. That announcement consisted of a brief blog post written by Zuckerberg that thanked Facebook users for the company’s success.
The announcement, however, was the only humble thing about Facebook at the time. It took the site six and a half years to record its first 500 million users, and just 26 months to do it again. By then, users had uploaded more than 219 billion photos to the site and clicked "Like" more than 1.13 trillion times.