Superstring theory is an attempt to unite the various string theories that have been suggested since the 1960s in a single, comprehensive explanation of observed phenomena in physics. String theories assume that, in place of elemental particles, the matter in the universe is made up of one-dimensional strings that are very short and carry high values of energy.
Superstring theory sums up the findings of earlier string theories by assuming a universe with at least 10 and possibly 12 dimensions. In this view, all of the matter, as well as the forces that act upon it, is composed ultimately of strings that are free to travel over the multidimensional geometry of the universe. By ducking in and out of observable space-time, and by interacting with each other in ways that can be described by modern mathematics, it is possible that supersymmetrical strings can account for most, if not all, of the known interactions in the universe.
No comprehensive superstring theory has successfully unified all of the basic forces. Some models produce results in unifying some of the forces, but gravity remains difficult to unify with the strong force and the electroweak force. Much of the research at the Large Hadron Collider (LHC) has focused on experimentally validating superstring theory.