- Massless states of the string compose all of the physical reality observed in our world.
- Masses of observed particles are a 'soft' effect originating at large distances.
- Spacetime is at least 10-dimensional.
- String theory provides a quantum theory of gravity and unifies all the interactions and constituents into a single entity.

Some important unsolved questions are :

- How to compactify 10 dimensions to 6+4 dimensions? Alternatively, is our world a 3-brane?
- What is happening at distances smaller than
10
^{-35}m? - How do we experimentally verify the existence of strings?
- We need to develop new mathermatics in areas of algebraic geometry, Riemann surfaces, affine Lie algebras, singular geometries, number theory and so on.

Last updated: 06 March, 2000