#79 : Wobbly Skyscrapers?
An optical illusion, or visual illusion is characterised by visually perceived images that differ from objective reality. What does this mean? Basically your eyes see one thing, and your brain 'sees' something else. The information that your eyes feed back to the brain has to be understood by the brain, and the brain is very clever at guessing what it should be seeing and sometimes this difference can be quite astounding.