Op art, also known as optical art, is a style of visual art that makes use of optical illusions.

"Optical art is a method of painting concerning the interaction between illusion and picture plane, between understanding and seeing." Op art works are abstract, with many of the better known pieces made in only black and white. When the viewer looks at them, the impression is given of movement, hidden images, flashing and vibration, patterns, or alternatively, of swelling or warping.

Op art is derived from the constructivist practices of the Bauhaus. This German school, founded by Walter Gropius, stressed the relationship of form and function within a framework of analysis and rationality. Students were taught to focus on the overall design, or entire composition, in order to present unified works. When the Bauhaus was forced to close in 1933, many of its instructors fled to the United States where the movement took root in Chicago and eventually at the Black Mountain College in Asheville, North Carolina, where Anni and Josef Albers would come to teach.^{[citation needed]}

Art is a term that describes a diverse range of human activities and the products of those activities, but is most often understood to refer to painting, film, photography, sculpture, and other visual media. Music, theatre, dance, literature, and interactive media are included in a broader definition of art or the arts. Until the 17th century, art referred to any skill or mastery and was not differentiated from crafts or sciences, but in modern usage the fine arts are distinguished from acquired skills in general.

Many definitions of art have been proposed by philosophers and others who have characterized art in terms of mimesis, expression, communication of emotion, or other values. During the Romantic period, art came to be seen as "a special faculty of the human mind to be classified with religion and science".

The nature of art, and related concepts such as creativity and interpretation, are explored in a branch of philosophy known as aesthetics.

The Encyclopædia Britannica Online defines art as "the use of skill and imagination in the creation of aesthetic objects, environments, or experiences that can be shared with others". By this definition of the word, artistic works have existed for almost as long as humankind: from early pre-historic art to contemporary art; however, some theories restrict the concept to modern Western societies. The first and broadest sense of art is the one that has remained closest to the older Latin meaning, which roughly translates to "skill" or "craft." A few examples where this meaning proves very broad include artifact, artificial, artifice, medical arts, and military arts. However, there are many other colloquial uses of the word, all with some relation to its etymology.