Humor is the ability or quality of people, objects, or situations to evoke feelings of amusement in other people. The term encompasses a form of entertainment or human communication which evokes such feelings, or which makes people laugh or feel happy. The origin of the term derives from the humoral medicine of the ancient Greeks, which stated that a mix of fluids known as humors.
Another explanation is that humor frequently contains an unexpected, often sudden, shift in perspective. Nearly anything can be the object of this perspective twist.