Facebook has become very successful due to several key factors: 1. It quickly adapted to changing user needs by shifting to a text-based platform suitable for mobile use. 2. It solved problems with early social networks by focusing on real identities and privacy controls to report abusive content. 3. Its semantic search system prioritizes the opinions of friends a user connects with on the site. 4. It developed new revenue models like social games and shopping that generate profits beyond advertisements.