An illusion is a distortion of the senses, revealing how the brain normally organizes and interprets sensory stimulation. While illusions distort reality, they are generally shared by most people. Illusions may occur with more of the human senses than vision, but visual illusions, optical illusions, are the most well known and understood. [Wikipedia]
Here you can find some interesting illusions:
sample of color illusion:
interesting!
have fun and (research!)
