A cartoon is a form of two-dimensional illustrated visual art. While the specific definition has changed over time, modern usage refers to a typically non-realistic or semi-realistic drawing or painting intended for satire, caricature, or humor, or to the artistic style of such works. An artist who creates cartoons is called a cartoonist. The concept originated in the Middle Ages and first described a preparatory drawing for a piece of art, such as a painting, fresco, tapestry, or stained glass window. In the 19th century, it came to refer to humorous illustrations in magazines and newspapers, and in the early 20th century and onward it referred to comic strips and animated films.