So, um, where do those, er, filler words come from? Discourse particles, as they’re also known, are used to fill those gaps when we’re thinking of what to say but don’t want to lose our turn in a conversation. English isn’t the only language that has them, either. Spanish speakers often use este, and in Japanese, it’s eto. Michael Erard has written at length about the subject in his book Um…: Slips, Stumbles, and Verbal Blunders, and What They Mean. This is part of a complete episode.