Humour or humor 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, controlled human health and emotion.
Humour can be a way of dealing with the menacing or unpleasant: Sprayed comment below a memorial plaque for Alois Alzheimer who first described the memory-damaging Alzheimer's disease – the German text means "Alois, we will never forget you!"
Boris Yeltsin and Bill Clinton enjoying a joke, in spite of their language differences
A person working in a retail store wearing a large pair of pants in an attempt to amuse those around them
A man laughing
Laughter is a pleasant physical reaction and emotion consisting usually 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 rise from such activities as being tickled, or from humorous stories, imagery, videos or thoughts. Most commonly, it is considered an auditory expression of a number of positive emotional states, such as joy, mirth, happiness, or relief. On some occasions, however, it may be caused by contrary emotional states such as embarrassment, surprise, or confusion such as nervous laughter or courtesy laugh. Age, gender, education, language, and culture are all indicators as to whether a person will experience laughter in a given situation. Other than humans, some other species of primate show laughter-like vocalizations in response to physical contact such as wrestling, play chasing or tickling.
A child laughing
A woman laughing
A man laughing
Laughter is a common response to tickling