Laughter communicates

The laugh might be the most versatile of all elements of human communication. Think of the many "meanings" - and implicative names - we attach to a supposedly simple interpersonal signal. The situation in which someone laughs, the timing, the nature of the interaction that's going on, the people present, their recent history, their shared experience - all give meaning to a laugh. A laugh can be playful, fearful, encouraging, sarcastic, snide, innocent, belligerent, placating, etc. In its simplicity - and its complexity - a laugh may be the most intricate of all of our methods of signaling.