Humour or humor (see spelling differences) is the tendency of particular cognitive 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 humourous (Latin: húmor, “body fluid”), control human health and emotion. People of all ages and cultures respond to humour. The majority of people are able to experience humour, i.e., to be amused, to laugh or smile at something funny, and thus they are considered to have a sense of humour.