See: Mathematics of humor for: Joke (given name)

A joke is a short story or ironic depiction of a situation communicated with the intent of being humorous. These jokes will normally have a punch line that will end the sentence to make it humorous. A joke can also be a single phrase or statement that employs sarcasm. The word joke can also be used as a slang term for a person or thing which is not taken seriously by others in general or is known as being a failure. A practical joke or prank differs from a spoken one in that the major component of the humour is physical rather than verbal (for example placing salt in the sugar bowl).

Jokes are typically for the entertainment of friends and onlookers. The desired response is generally laughter; when this does not happen the joke is said to have "fallen flat".

Antiquity of jokes

Jokes have been a part of human culture since at least 1900 BCE. A fart joke from ancient Sumer is currently believed to be the world's oldest known joke

Anthropology of jokes

In 1975 anthropologist Mary Douglas noted that "Joking as one mode of expression has yet to be interpreted in its total relation to other modes of expression"; scholar Seth Graham remarked that 30 years later this statement remains largely valid.

Psychology of jokes

Why we laugh has been the subject of serious academic study, examples being:

• Immanuel Kant, in Critique of Judgement (1790) states that "Laughter is an effect that arises if a tense expectation is transformed into nothing." Here is Kant's 218-year old joke and his analysis:

"An Englishman at an Indian's table in Surat saw a bottle of ale being opened, and all the beer, turned to froth, rushed out. The Indian, by repeated exclamations, showed his great amazement. - Well, what's so amazing in that? asked the Englishman. - Oh, but I'm not amazed at its coming out, replied the Indian, but how you managed to get it all in. - This makes us laugh, and it gives us a hearty pleasure. This is not because, say, we think we are smarter than this ignorant man, nor are we laughing at anything else here that it is our liking and that we noticed through our understanding. It is rather that we had a tense expectation that suddenly vanished..."

• Henri Bergson, in his book Le rire (Laughter, 1901), suggests that laughter evolved to make social life possible for human beings.
• Sigmund Freud's "Jokes and their Relation to the Unconscious". (Der Witz und seine Beziehung zum Unbewußten).
• Arthur Koestler, in The Act of Creation (1964), analyses humour and compares it to other creative activities, such as literature and science.
• Marvin Minsky in Society of Mind (1986).

Marvin Minsky suggests that laughter has a specific function related to the human brain. In his opinion jokes and laughter are mechanisms for the brain to learn nonsense. For that reason, he argues, jokes are usually not as funny when you hear them repeatedly.