Optical illusion is also known as visual illusion. In this optical illusion, the images of the objects are perceived differently than they really are. When the eyes gather information, it gets processed in the brain which does not match with the actual physical measurement of the source for which the information has been sent to the brain. The visual optical illusions are of different types- literal optical illusions- the images created are different from the real object; physiological optical illusions- the excessive stimulation of a particular type- color, size, position or movement effect the working of eye and brain thus the image is differently perceived than the objects; the third type is the cognitive illusions which is caused due to unconscious references. Optical illusions can occur naturally or it could be shown using some visual tricks. One very common example of the optical illusion is the mirage in the desert areas which is seen or heard by many of us. The size of the moon seems to vary but actually the size of the moon does not change. When the moon is over our head, it looks smaller but if we look at the moon near the horizon, it looks larger. The changing size of the moon is a natural illusion and it is categorized as cognitive or perceptual illusion. There are many examples of visual optical illusions such as Necker tube, Café wall illusion, Penrose triangle etc. Since early ages, artists have been using optical illusions to create some masterpieces.