Facebook, the groundbreaking social media platform cofounded by CEO Mark Zuckerberg, was launched on February 4, 2004.
Zuckerberg was a sophomore at Harvard University when he built Facebook with fellow students Eduardo Saverin, Andrew McCollum, Dustin Moskovitz, and Chris Hughes.
Here's what the original Facebook — sorry, "The" Facebook — layout looked like when it launched in 2004.
Within a month of the launch, half of Harvard students were Facebook members. Zuckerberg dropped out of school in 2004 to focus on growing the business.
Facebook moved to a tiny office in Palo Alto, California, and by May 2005, had secured nearly $14 million in funding. The New York Times hailed Zuckerberg has a "21-year-old whiz kid."
As Facebook rapidly grew, so did Zuckerberg's wealth. In 2008, he cracked Forbes' World Billionaires List for the first time, with a net worth of $1.5 billion. He was the youngest of the 1,125 billionaires on the list.
That same year, Facebook settled a lawsuit with former Harvard classmates Cameron and Tyler Winklevoss and Divya Narendra, who had alleged that Zuckerberg had stolen their idea for Facebook from their social media platform Connect U. As part of that settlement, they received 1.2 million Facebook shares.
Over the next few years, Zuckerberg took up political causes, including advocating for the spreading of internet access around the world.
In 2012, Zuckerberg hit a career milestone as Facebook debuted on the New York Stock Exchange. At the time, it was the biggest technology IPO in history.
Over the next few years, Zuckerberg would flex his business skills by making some shrewd tech acquisitions. Facebook bought Instagram for $1 billion in 2012 and WhatsApp for $19 billion in 2014.
Facebook also acquired the VR company Oculus in March 2014 for $2 billion.
By the end of 2014, Zuckerberg's net worth had shot up to $30 billion, and would steadily increase over the next three years.
A new phase of Zuckerberg's career began in 2015 when he and his wife Priscilla Chan launched the Chan Zuckerberg Initiative. The couple pledged to give 99% of the value of their Facebook shares to the philanthropic venture to "advance human potential and promote equality."
In 2017, Zuckerberg seemed to be flirting with a career in politics as he embarked on a whirlwind tour of the US. He was photographed working on a Ford assembly line in Michigan, visiting a Civil War battlefield in Mississippi, and attending a church service in South Carolina, among other destinations.
But at the same time, Facebook was coming under intense scrutiny for its role in disseminating fake news and misinformation during the 2016 presidential election.
In 2018, it was revealed that the British consulting firm Cambridge Analytica acquired the personal data of 87 million Facebook users in an effort to tilt the election to Donald Trump.
Zuckerberg addressed the scandal in a testimony before Congress in April 2018, saying, "we have made a lot of mistakes in running the company. I think it's pretty much impossible, I believe, to start a company in your dorm room and then grow it to be at the scale that we're at now without making some mistakes.”
In the 10 days following the initial report on the Cambridge Analytica scandal, Zuckerberg's net worth dropped from $75 billion to $62.2 billion, according to Bloomberg.
Zuckerberg's leadership again came into question in November 2018, when an explosive New York Times report said Facebook knew about Russian efforts to interfere in the US election as early 2016, but waited more than a year to share the information.
The report also said Facebook's chief operating officer Sheryl Sandberg led a lobbying campaign to deflect criticism of the company onto rival tech firms and billionaire liberal donor George Soros.
As Facebook stock steadily dropped starting in July, a defiant Zuckerberg told CNN in November he had no intentions of stepping down as Facebook's CEO.
By the end of 2018, Zuckerberg's net worth had hit a three-year low of $49.4 billion. But it's rebounded since then, and now sits around $65.6 billion, making him the fifth-richest person in the world.
As Facebook hits its 15th birthday, the company faces an uncertain future. There's no question Mark Zuckerberg has come a long way since he launched the site out of his Harvard dorm room in 2004.