Humour or humor (see American and British English spelling differences) is the tendency of particular cognitive experiences to provoke laughter and provide amusement. Many theories exist about what humour is and what social function it serves. People of all ages and cultures respond to humour. The majority of people are able to be amused, to laugh or smile at something funny, and thus they are considered to have a "sense of humour."

The term derives from the humoral medicine of the ancient Greeks, which stated that a mix of fluids known as humours (Greek: χυμός, chymos, literally juice or sap; metaphorically, flavour) controlled human health and emotion. (This theory has since been found to be counterfactual.)Fact: date=April 2009

A sense of humour is the ability to experience humour, although the extent to which an individual will find something humorous depends on a host of variables, including geographical location, culture, maturity, level of education, intelligence, and context. For example, young children may possibly favour slapstick, such as Punch and Judy puppet shows or cartoons (e.g., Tom and Jerry). Satire may rely more on understanding the target of the humour, and thus tends to appeal to more mature audiences. Nonsatirical humour can be specifically termed "recreational drollery."

Understanding humour

Arthur Schopenhauer lamented the misuse of the term "humour" (a German loanword from English) to mean any type of comedy. However, both "humour" and "comic" are often used when theorizing about the subject. The connotation of "humour" is more that of response, while "comic" refers more to stimulus. "Humour" also originally had a connotation of a combined ridiculousness and wit in one individual, the paradigm case being Shakespeare's Sir John Falstaff. The French were slow to adopt the term "humour," and in French, "humeur" and "humour" are still two different words, the former still referring only to the archaic concept of humours.

Western humour theory begins with Plato, who attributed to Socrates (as a semihistorical dialogue character) in the Philebus (p. 49b) the view that the essence of the ridiculous is an ignorance in the weak, who are thus unable to retaliate when ridiculed. Later, in Greek philosophy, Aristotle, in the Poetics (1449a, pp. 34–35), suggested that an ugliness that does not disgust is fundamental to humour.

In ancient Sanskrit drama, Bharata Muni's Natya Shastra defined humour (hāsyam) as one of the eight nava rasas, or principle rasas (emotional responses), which can be inspired in the audience by bhavas, the imitations of emotions that the actors perform. Each rasa was associated with a specific bhavas portrayed on stage. In the case of humour, it was associated with mirth (hasya).