In visual art, the term kinetic art, derived from the Greek word kinesis, refers to works that incorporate real or apparent movement. It explores how things look when they move, so in its widest definition, kinetic art embraces a huge number of different art forms, as well as media types and styles. Thus, for instance, it may include cinematic and animation art, happenings and other types of performance art such as mime, clockwork/ clocktower figurines, stroboscopic or light-related artworks (Lumino Kinetic art), land art or any artifact that disappears (snowman) or undergoes a process of visual change, robotic art, motion graphics and other artworks created with new media technologies. It also incorporates Op art paintings, drawings and prints, whose 'motion' is merely an optical illusion. The most famous works of Kinetic art, however, are various types of hand-powered or motor-powered sculpture by Jean Tinguely, and mobiles invented by Alexander Calder, whose movement is caused by air currents.