Suspension of disbelief

Suspension of disbelief is the willingness for a person to accept fantasy as it is presented to them in any form of media.
Reality and fantasy.
Reality is the world around us. Fantasy is a world that only is in our minds, or recorded in some way onto or into something that can be passed along from one form to another. Fantasy cannot exist as something real, something that we can touch or see as it is. 
An example of something from fantasy is the White Rabbit from Lewis Carroll's "Alice in Wonderland". Because of our experience, that is, how we have lived our lives, it has not been proven that it can possibly be real. The White Rabbit is an animal which stands on two legs (in some stories), wears human clothing, and acts and speaks like a human. For us as humans, a normal rabbit does not speak, nor does it act or speak like a human. Because of that, we think of the White Rabbit as fantasy, it only can be living in a not-real world.
Suspension of disbelief is a way to enjoy a story. If one were to completely disregard a story as false, the entertainment value, what makes us like a story, would be lost. On the other hand, if one accepts a story as real for as long as the story goes on, then a connection to living in reality can be made, however big or small.