Facebook's Mark Zuckerberg WILL testify before Congress on how the data of millions of people was used. #FB #Facebook #MarkZuckerberg #data #socialmedia #CambridgeAnalytica #MySpace #poke #news #2016election #DonaldTrump #Trump #election #Obama #BarackObama #scandal #UK #GreatBritain #England #Parliament #USCongress #Congress #USA #UnitedStates #testimony