Yes, superstring theory is one of the most widely studied areas of research in theoretical physics. Essentially, superstring theory postulates that every elementary particle (seen as points) is actually a loop (a superstring - super comes from something known as supersymmetry) that vibrates. It vibrates due to the fact that it wants to have the lowest amount of potential energy, much like a spring. Superstring theory is able to incorporate General Relativity into Quantum Field Theory by having a string vibration mode that is a spin 2, massless particle, a graviton. It is spin-2 because the Stress-Energy tensor is a second-rank tensor. Although, superstring theory can be generalized to M-Theory which is a theory of M2-branes and M5-branes but this isn't necessary to know for the sake of my argument. In order for superstring theory/m-theory to be consistent the framework needs 11 space-time dimensions. The extra dimensions are accepted within the string community to be compactified at each point in space into Calabi-Yau Manifolds.
I hope this helped.