HARI SREENIVASAN:

More than ever before, a big part of this election campaign has played itself out on social media.

No doubt the candidates and their campaigns have tried to take advantage of these platforms. But there's been a much bigger role this year as well for unseen players. You might call it the rise of the bots.

Miles O'Brien has the story, part of our weekly reporting about on the Leading Edge of science and technology.

HILLARY CLINTON (D), Presidential Nominee: Donald supported the invasion of Iraq.

DONALD TRUMP (R), Presidential Nominee: Wrong.