We show how extensions of conventional differential geometry, so called "generalised geometry", give a natural way of formulating type II and eleven-dimensional supergravity theories, unifying the bosonic fields and symmetries. There is a natural action of the U- and T-duality groups E_d(d) and O(d,d) and the formalism shows that the supergravity theories have an enhanced local symmetry. By introducing the analogue of the Levi-Civita connection we find that the action and equations of motion simplify, writable in terms of a generalised Ricci tensor. The connection also encodes the supersymmetry variations and fermionic equations of motion. There are interesting implications for describing supersymmetric backgrounds and connections to the embedding tensor formalism.
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