11D Supergravity and Hidden Symmetries

We review the structure of maximal $D=11$ and $D=10$ supergravities. Upon dimensional reduction, these theories give rise to the unique maximal supergravities in all lower spacetime dimensions $D<10$. In $D$ dimensions, maximal supergravity exhibits the exceptional global symmetry group E$_{11-D}$, part of which is realized as hidden symmetries and only manifest after proper dualization of the fields. We also briefly review the reformulation of $D=11$ supergravity as an exceptional field theory which renders the appearance of hidden symmetries manifest.