Generalised geometry provides an elegant geometrical formulation of the supergravity theories underlying string theory and M theory. In this contribution, we review recent work showing that general supersymmetric flux backgrounds can be described as the analogue of special holonomy manifolds in this new geometry. The Killing superalgebra, which has a neat manifestation in this language, plays a key role in the proof of the result for $\mathcal{N} > 2$ supersymmetry and its form can be fixed explicitly using this technology.