Facebook is a powerful social networking platform with over 500 million users worldwide. Its reach and viral nature allow it to spread messages across the internet. The document discusses 5 key factors, or "x-factors", that make Facebook unique for marketing: 1) Connection - Facebook allows users to connect with others from all walks of life. 2) Self-expression - Users represent themselves through their profile and what they like. 3) Entertainment - Facebook is an entertaining platform users enjoy for fun and passing time. 4) Discovery - Facebook enables accidental discoveries of new people, brands, and ideas. 5) Mobilization - When these factors combine, they have potential to ignite viral marketing and spread brands' messages widely.