Mark Zuckerberg · 2004
Facebook is an American social networking service founded in 2004 by Mark Zuckerberg and four Harvard College roommates; initially limited to Harvard students, it expanded to other North American universities and then globally to users aged 13+ (14+ in select regions) starting in 2006; as of December 2023 it had ~3.07 billion monthly active users and as of July 2025 ranked third globally by web traffic, with 23% originating from the US; it was the most downloaded mobile app of the 2010s and is accessible across internet-connected devices including PCs, tablets, and smartphones; its headquarters are in Palo Alto, California.
