The Hermann Grid is an optical illusion that consists of a grid of black squares on a white background. When viewed, it creates the perception of gray dots appearing at the intersections of the white lines, even though no such dots are present. This phenomenon occurs due to the way our visual system processes contrast and edges. The illusion was first described by the German psychologist Hermann in 1870. It highlights how our brains interpret visual information, often leading to misperceptions. The Hermann Grid is commonly used in studies of visual perception and is a popular example in psychology and art.