Facebook is an online social networking service was founded on February 4, 2004, by Mark Zuckerberg with his college roommates and fellow Harvard University students Eduardo Saverin, Andrew McCollum, Dustin Moskovitz and Chris Hughes. Facebook now allows anyone who claims to be at least 13 years old worldwide to become a registered user of the website, although proof is not required.
Are you thinking everyone using face book freely so how does facebook make money ? check below infographic which explain you how does facebook make billion dollars money per year.