Samantha's Question - The Matrix

Ok basically I'm just asking what is reality? And is reality defined by whatever is not reality? Like in dreams, hallucinations, imagination etc. So we can say our present state is reality. But then the philosophical question is that (I know this is going to sound ridiculous) how do we know we are not all "brains in a vat" controlled by a Evil Genius who makes us think whatever we are feeling is really reality, i.e. How do we know we're not trapped in "The Matrix"?

OK Guys and Gals . . . make this blog work!

Pour in your thoughts.