CNBC's Lester Holt delivers a comprehensive look at how this Internet phenomenon, with half a billion users, is affecting society in ways most people are unaware of.

From a girl who is reunited with her birth mother with the help of Facebook, to a woman who lost her job because of her online postings, "The Facebook Obsession" examines how the site is fundamentally altering American life for better or worse; even the White House and many police departments have their own Facebook pages. Holt explores the intense privacy debate that Facebook has provoked, and explains the business model that has turned a dorm-room venture into a multi-billion dollar enterprise.