Humor Encyclopedia Britannica

title: "humour | Definition, Types, Examples, & Facts"
description: "humour,  communication in which the stimulus produces amusement. In all its many-splendoured varieties, humour can be simply defined as a type of stimulation that tends to elicit the laughter reflex. Spontaneous laughter is a motor reflex produced by the coordinated contraction of 15 facial muscles in a stereotyped pattern and accompanied by altered breathing. Electrical stimulation of the main lifting muscle of the upper lip, the zygomatic major, with currents of varying intensity produces facial expressions ranging from the faint smile through the broad grin to the contortions typical of explosive laughter. The laughter and smile of civilized man is,"