Facebook is a marketing book

Facebook Usage Stats (source SocialMediaExaminer)

• Shared content: 3.5 billion/week
• Photos uploaded: 2.5 billion/month
• Videos uploaded: 14 million/month (more than 19,000 per hour!!)
• Events created: 3.5 million/month
• Users who have signed on with Facebook Connect: 80 million total across 80,000 websites since it launched in December 2008

Facebook is definitely a social platform to both web and mobile.
More than just a social network, it even became the vehicle for a change of habits on the Internet, changes illustrate the growing power of sharing and personalized recommendation, whether branded or individuals.