Twitter made its debut on the New York Stock Exchange in November. Both the social media giant and the relative newcomer Snapchat are valued in the billions, but neither company has yet turned a profit.
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"DOUGH a crust, an unbaked crust ...": Carrie Underwood may have played Maria in NBC's The Sound of Music Live, but on Twitter, it was @DiGiorno that stole the show.
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In this Nov. 8, 2011, photo, NASA fan David Parmet signs his name on a Twitter logo during a tweetup event for about 50 of NASA's Twitter followers at the Langley Research Center in Hampton, Va.