Op art, short for Optical Art, consists of works that feature optical effects especially optical illusions. For instance, some of the paintings of Bridget Riley convey a sense of motion despite being static, and some of her other pieces give the illusion of color despite being done in only black and white. Other terms for this genre are geometric abstraction, hard-edge abstraction, retinal art and perceptual abstraction. The terms geometric and hard-edge abstraction refer firstly that the works are abstract (as opposed to representational), and secondly geometric, regular, mathematical (as opposed to organic). The terms retinal art and perceptual abstraction refer to the viewer's response to the work.

The term "Op Art" was coined by the sculptor George Rickey in 1964 during a conversation with two Museum of Modern Art (MoMA) curators, William Seitz and Peter Selz. The term first appeared in print in an article in Time magazine in October of the same year. The genre's emphasis on vibrant color and pattern clearly found its way into the design and fashion of the 1960's. As an identified, pure art movement, Op Art was short-lived – its pinnacle occuring in 1965 with MoMA's exhibition entitled The Responsive Eye. On the other hand, works by Victor Vasarely dating from the 1930's and by John McHale in the 1950's have characteristics in common with Op Art.

A predecessor of Op Art is found in some artists working in the Bauhaus movement. The Bauhaus was primarily a school, founded by the architect Walter Gropius, which existed in Germany between the World War I and World War II. The school stressed the connection between art and craft as well as that between function and design. A sequence of instructors, including Johannes Itten, Wassily Kandinsky, Paul Klee, and Josef Albers developed analytical exercises for studying shape and color that often became works in their own right. When the Nazi regime closed the school in 1933, some of the instructors, most notably Anni and Josef Albers, emmigrated to the United States and taught there, influencing generations of U.S. artists.

Sources: http://en.wikipedia.org/wiki/Op_art and ArtSpeak by Robert Atkins.