Laughter

Laughter is a physical reaction in humans and some species of primate, consisting typically of rhythmical, often audible contractions of the diaphragm and other parts of the respiratory system. It is a response to certain external or internal stimuli. Laughter can arise from such activities as being tickled,^[1] or from humorous stories or thoughts.^[2] Most commonly, it is considered a visual expression of a number of positive emotional states, such as joy, mirth, happiness, relief, etc. On some occasions, however, it may be caused by contrary emotional states such as embarrassment, apology, or confusion "nervous laughter" or courtesy laugh. Factors such as age, gender, education, language, and culture are factors^[3] as to whether a person will experience laughter in a given situation.