Facebook is a social networking website, that was launched on February 4, 2004. Facebook was founded by Mark Zuckerberg, a member of the Harvard class of 2006 and former Ardsley High School student. Initially the membership was restricted to students of Harvard College. It was subsequently expanded to all Ivy League schools within two months. Many individual universities were added in rapid succession over the next year. Eventually, people with a university (e.g .edu, .ac.uk, etc.) email address from institutions across the globe were eligible to join. Networks were then initiated for high schools and some large companies. Since September 11, 2006, anyone 13 or older may join.[2][3] Users can select to join one or more participating networks, such as a high school, place of employment, or geographic region.
As of late November 2007, the website has the largest number of registered users among college-focused sites,[citation needed] with 55 million active members (including non-collegiate members) worldwide,[4] with membership expected to surpass 60 million users by the end of the year.[5] From September 2006 to September 2007 the site's traffic ranking increased from 60th to 7th, according to Alexa.[6] It is the number one site for photos in the United States, ahead of public sites such as Flickr,[citation needed] with over 60 million photos uploaded weekly.[7][8]
