An optical illusion is a visual phenomenon that tricks the brain into seeing something that is not there or misinterpreting what is seen. These illusions occur when the brain processes visual information in a way that differs from reality, often due to the arrangement of colors, shapes, and patterns. There are various types of optical illusions, including geometric illusions, motion illusions, and ambiguous images. Each type plays with perception, leading viewers to see movement, depth, or different images depending on their focus. Optical illusions are often used in art and psychology to explore how we perceive the world around us.