What is String Theory

What exactly is String Theory? Can anyone explain it to me from the perspective of an average man in the street?

How valid is the theory?

The following link is a break down of string theory. its not very technical and is easy to grasp. as to the validity of it well, string theory has received far more attention in the public arena than anything since einstein & relativity. but bear in mind that string theory is a theory of fundamental physics, and far removed from the world of practical application. good luck! http://superstringtheory.com/basics/basi…