What's the difference between string theory, super-string theory and M-theory?

Question

I used to think they describe the same thing.

Answer 1

well : they are related to "Physics absolutely Answers  

Science & Mathemathics just Algebra theory  "

Answer 2

String theory is an attempt at explaining all the subatomic particles as behaving like 1 dimensional strings that vibrate and are extremely small (planck length).  There are many different but similar theories, usually five are recognized but they other hybrid theories as well.  Superstring theory attempts to explain all the particles and forces and it differs from string theory because it incorporates fermions and supersymmetry also. Bosonic string theory does not do this.

M theory attempts to unify the 5 string theories, because these theories are similar but have some very important differences and each can explain some observations but not all observations. Basically these theories believe that multi-dimensional membranes are responsible for the behaviors seen of subatomic particles and are  attempts to define a unified theory of matter and subatomic forces.  As of yet we can't incorporate the physical laws of macrocosms with the apparent behavior of subatomic particles (quantum mechanics and general relativity) and many physicists believe that there has to be a theory that explains it all since these are part of the same thing.  These theories are very complicated and very technical. But the attempt is to unify all the different forces and known particles into a theory that can explain all these behaviors using the same language.  And possibly give insight as how to convert one into the other.