Humour (British English) or humor (American English; see spelling differences) is the tendency of experiences to provoke laughter and provide amusement. The term derives from the humoral medicine of the ancient Greeks, which taught that the balance of fluids in the human body, known as humours (Latin: humor, "body fluid"), controlled human health and emotion.
People of all ages and cultures respond to humour. Most people are able to experience humour—be amused, smile or laugh at something funny—and thus are considered to have a sense of humour. The hypothetical person lacking a sense of humour would likely find the behaviour inducing it to be inexplicable, strange, or even irrational. Though ultimately decided by personal taste, the extent to which a person finds something humorous depends on a host of variables, including geographical location, culture, maturity, level of education, intelligence and context. For example, young children may favour slapstick such as Punch and Judy puppet shows or the Tom and Jerry cartoons, whose physical nature makes it accessible to them. By contrast, more sophisticated forms of humour such as satire require an understanding of its social meaning and context, and thus tend to appeal to a more mature audience.
Many theories exist about what humour is and what social function it serves. The prevailing types of theories attempting to account for the existence of humour include psychological theories, the vast majority of which consider humour-induced behaviour to be very healthy; spiritual theories, which may, for instance, consider humour to be a "gift from God"; and theories which consider humour to be an unexplainable mystery, very much like a mystical experience.
The benign-violation theory, endorsed by Peter McGraw, attempts to explain humour's existence. The theory says 'humour only occurs when something seems wrong, unsettling, or threatening, but simultaneously seems okay, acceptable or safe'. Humour can be used as a method to easily engage in social interaction by taking away that awkward, uncomfortable, or uneasy feeling of social interactions.
Others believe that 'the appropriate use of humour can facilitate social interactions'.
Some claim that humour cannot or should not be explained. Author E.B. White once said, "Humor can be dissected as a frog can, but the thing dies in the process and the innards are discouraging to any but the pure scientific mind." Counter to this argument, protests against "offensive" cartoons invite the dissection of humour or its lack by aggrieved individuals and communities. This process of dissecting humour does not necessarily banish a sense of humour but begs attention towards its politics and assumed universality (Khanduri 2014).
Arthur Schopenhauer lamented the misuse of humour (a German loanword from English) to mean any type of comedy. However, both humour and comic are often used when theorising about the subject. The connotations of humour as opposed to comic are said to be that of response versus stimulus. Additionally, humour was thought to include a combination of ridiculousness and wit in an individual; the paradigmatic case being Shakespeare's Sir John Falstaff. The French were slow to adopt the term humour; in French, humeur and humour are still two different words, the former referring to a person's mood or to the archaic concept of the four humours.