Op art, short for optical art, is a style of visual art that uses distorted or manipulated geometrical patterns, often to create optical illusions. It began in the early 20th century, and was especially popular from the 1960s on, the term "Op art" dating to 1964. Op artworks are normally abstract, with some better-known pieces created in black and white. Typically, they give the viewer the impression of movement, hidden images, flashing and vibrating patterns, or swelling or warping. In contrast, the much older trompe-l'œil style always represents figurative subjects, which are shown with deceptive three-dimensionality. Source: Wikipedia (en)