Facebook Active User Growth
This chart shows the number of monthly active Facebook users worldwide. Statista / IBT

Over 15 years ago, on February 4, 2004, then-19-year old Harvard student Mark Zuckerberg, along with some of his classmates, launched a little website called Thefacebook.

"Thefacebook is an online directory that connects people through social networks at colleges", the original website greeted its visitors back then, explaining that it would enable them to "search for people at your school, find out who are in your classes [sic], look up your friends’ friends and see a visualization of your social network."

Confined to the Harvard campus at first, the service quickly gained popularity and was subsequently rolled out to other colleges. By the end of 2004, Thefacebook had more than 1 million registered users and the newly-founded company behind it had not only moved to Silicon Valley but also secured a $500,000 investment from PayPal co-founder Peter Thiel. After changing its name to just "Facebook" in 2005, the social network was opened to the general public in the fall of 2006, marking the start of one of the most remarkable growth stories in corporate history.

Within three years, the social network added 350 million users. In the summer of 2012, it became the first online service of its kind to reach 1 billion monthly active users.

Despite being shrouded in controversy over its (mis)handling of user privacy, Facebook continues to grow. In the third quarter of 2019, Facebook brought its total user base to an astonishing 2.45 billion.

“We had a good quarter and our community and business continue to grow,” said Facebook CEO Mark Zuckerberg in a statement on October 30. “We are focused on making progress on major social issues and building new experiences that improve people’s lives around the world.”