Mark Elliot Zuckerberg, a 19-year-old computer whiz at Harvard University, worked out of his dormitory room on an online network aimed initially at connecting Harvard students.
Thefacebook.com was launched by Zuckerberg and three Harvard roommates and classmates: Chris Hughes, Eduardo Saverin and Dustin Moskovitz.
The new company received its first investment $500,000 from PayPal co-founder Peter Thiel.
Year 2005-07: Journey from Thefacebook.com to Facebook
Thefacebook.com officially changed its name to Facebook in 2005.
Yahoo made an unsuccessful $1 billion bid for the social network in 2006.
The social networking site also added the 'News Feed' and opened up to anyone over the age of 13 in the same year.
While in 2007, Microsoft took a $240 million stake in Facebook, which had 50 million members.
Year 2008-09: Its ups and downs
In 2008 a $65 million settlement reached with twins Tyler and Cameron Winklevoss over allegations that Zuckerberg stole their idea for Facebook while at Harvard.
Sheryl Sandberg, a top Google executive, was hired as Facebook's chief operating officer in the same year. French and German Facebook sites were also launched in 2008.
Facebook dethroned MySpace to become the world's most popular social networking website, again in the same year.
Facebook membership reached 100 million after which it launched its first mobile application in the year 2009.
Year 2010-12: Facebook membership reaches 1 billion
In the year 2010, Facebook membership reached 500 million and Lady Gaga became the first with 10 million fans on Facebook.
In 2011 timeline pages were introduced that led Facebook users to turn their profiles into interactive digital scrapbooks that tell the stories of their lives.
In 2012, Facebook closed a deal to buy the popular photo-sharing app Instagram for $1 billion. Also, its membership topped to one billion in the same year.
Year 2013-15: Facebook collaborates with Microsoft, buys WhatsApp
In 2013, Facebook launched a "social graph" search engine to find posts on the network, in collaboration with Microsoft.
Whereas in 2014, it purchased smartphone messaging platform WhatsApp in cash and stock deal valued at $19 billion.
Facebook moved into its new Frank Gehry-designed headquarters in Silicon Valley, with a rooftop park and 'the largest open floor plan in the world' in 2015.
Year 2016-17: Facebook membership crosses 2 billion
In November 2016, Facebook and other social networks were embroiled in controversy over manipulation of online platforms by Russia to sow division and sway elections.
Being the part of controversies did not stop facebook to top two billion monthly users in 2017.
In the same year, Facebook revealed hundreds of fake profiles evidently orchestrated by Russia bought ads to fuel political tensions ahead of the recent presidential election.
Year 2018: Zuckerberg grilled in US Congress over handling of user data
In 2018, a scandal broke. British consulting firm Cambridge Analytica stealthily harvested personal data of millions of Facebook users and used it for political purposes including helping the campaign that resulted in the election of US President Donald Trump.
Zuckerberg was grilled in US Congress over Facebook's handling of user data and the social network being manipulated to undermine democracy.
Facebook's value based on the price of its shares reached an all-time high of nearly $628 billion.
Year 2019: Zuckerberg addresses heightened concerns about social media
As Facebook nears its 15th anniversary, Zuckerberg pledged 'public discussions about the future of technology in society' in his latest effort to address heightened concerns about social media.