This document discusses M-theory and its relation to string theory. Some key points: 1) M-theory is a theory in 11 dimensions that unifies the five 10-dimensional superstring theories. It reduces to 11-dimensional supergravity at low energies. 2) The document outlines the dimensional reductions of M-theory to the various string theories and their dualities (S-duality, T-duality, U-duality). 3) It presents the field contents and supersymmetries of M-theory compactified on a torus and its connections to the different string theories through dualities.