Mark Zuckerberg created Facebook in 2004 while he was a student at Harvard. He was inspired to create a social networking site after developing Facemash, a site that allowed users to rate other students' photos. Initially only available to Harvard students, Facebook quickly expanded to other universities and then publicly in 2006. By 2018, Facebook had over 2.2 billion active users worldwide. While Facebook allows users to connect and share with friends and family, it also faces criticisms like oversharing, bullying, and relationship problems caused by excessive use.