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Supergravity is a theory in which supersymmetry is a local symmetry, with transformation parameters depending on spacetime position. Making supersymmetry local introduces a spin-$3/2$ gauge field, the gravitino, alongside the graviton describing gravity.

The reason gravity appears is structural: two supersymmetry transformations include a translation, and local translations require a dynamical spacetime geometry. The number of supercharges and the spacetime dimension determine the allowed multiplets and interactions. Eleven-dimensional supergravity and type IIA supergravity are examples with different field content and dimensional settings.

Supergravity often serves as a low-energy effective field theory of a superstring or M-theory description. That role does not make a generic finite-derivative supergravity action a complete quantum theory at arbitrarily high energy. Its validity depends on the scales at which neglected higher-derivative and additional-state effects become important.

A supergravity multiplet is a supermultiplet containing a graviton and its supersymmetric partners. In four-dimensional N=8 supergravity, the irreducible massless supermultiplet contains $128$ boson and $128$ fermion states.

Quantum gravity with a two-dimensional spacetime or worldsheet. In the string formulation, one sums over surface metrics and topologies with matter fields on each surface. This worldsheet theory is distinct from the target-space gravity described by the graviton in the closed-string spectrum.