A zoetrope is a device that produces the illusion of motion through a series of drawings or photographs that are rapidly displayed in a circular fashion. There are few synonyms for the word zoetrope, but some variations may include: wheel of life, wonder wheel and optical toy. The term zoopraxiscope is also sometimes used, which is a more complex machine that uses a similar principle to the zoetrope but with the addition of a projecting lens. These devices were popular forms of entertainment in the 19th century, before the invention of motion pictures. Today, zoetropes are still used in the animation industry and as a unique form of art.