Facebook
Facebook was started by Mark Zuckerberg with his college roommates and fellow computer science students Eduardo Saverin, Dustin Moskovitz and Chris Hughes. The website's membership was only for Harvard students at first. Later it included other colleges in the Boston area, the Ivy League, and Stanford University. It eventually opened for students at other universities. After that, it opened to high school students, and, finally, to anyone aged 13 and over. Based on ConsumersReports.org in May 2011, there are 7.5 million children under 13 with accounts. This breaks the website's rules.