The
holographic correspondence is a powerful duality between a quantum theory of
gravity and a quantum gauge theory in one lower space-time dimension. Higher
spin gravity theories, i.e. gravity theories that also contain (gauge) fields
of spins greater than 2, play a special role in holography. I will explain
consistent interacting higher spin gravity theories in anti-de Sitter space,
their duality with gauged conformal vector models, and their connection to
string theory.