Abstract

I, someone who has entered string theory with a phenomenologists background, will attempt to give a gentle first introduction to what string theory or M theory actually is. Why does it unify gravity and gauge theory? Why are there 5 types of string theory and why do they live in 10 dimensions? Are they string theories anyway since they contain higher dimension branes? How do dualities and 11 dimensional M-theory unify them? How do we even define what these theories are? Are there really 10^500 vacuum states? Does any of this have anything to do with the real world? We can end with a good argument about the anthropic principle.