What is an optical illusion?
Optical illusions are images or pictures that we perceive differently than they really are. Put another way, optical illusions occur when our eyes send information to our brains that tricks us into perceiving something that does not match reality.
The word “illusion" comes from the Latin word illudere, which means “to mock."
http://wonderopolis.org/wonder/what-is-an-optical-illusion
Many people really enjoy looking at illusion. They seem to love being fooled in this way. Magicians use illusions all the time. In fact, magicians are sometimes referred to as illusionists.
