Facebook has spent the past 10 years building a business upon your personal information.

The social network knows a lot about you. Clearly, it knows what you've told it -- your age, location, martial status, job, etc.

But it also knows what you like. This is based partly on obvious things -- you clicking the like button -- but also on less obvious ones. What you talk about in your postings, what content you share, even how long your cursor hovers over a particular image.
"They know more about your tastes and preferences than any company ever has," said Nate Elliott, a social media analyst at the research firm Forrester.
The trick for Facebook -- which makes 90% of its money by selling ads -- is figuring out how to use this information to capture more of the $500 billion-plus spent on advertising each year, and to do it without alienating its user base.