On Aug. 6, 2012, the Twitter account @realDonaldTrump posted an important public announcement:
“An 'extremely credible source' has called my office and told me that @BarackObama's birth certificate is a fraud.”
Who was the source? (Why was “extremely credible source” in quotation marks?) Donald Trump didn’t say. Nor did he offer evidence to back up his claim. But out it went to his millions of Twitter followers — and you can still retweet it from Trump’s account, as Democratic presidential candidate Hillary Clinton’s official Twitter account did last weekend.