Facebook f8 developers conference

Associated Press
FILE - In this March 25, 2015 file photo, Mark Zuckerberg talks about the Messenger app during the Facebook F8 Developer Conference in San Francisco.  For the first time, a billion people used Facebook in a single day on Monday, Aug. 24, 2015. Zuckerberg marked the occasion with a post on his Facebook page, saying that one out of seven people on Earth logged in to the social network to connect with their friends and family. (AP Photo/Eric Risberg)

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Zuckerberg introduced the Facebook "timeline" Sept. 22 in San Francisco at the company's f8 conference for some 2,000 entrepreneurs, developers and journalists.

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