  The Black Hole Uncertainty Principle correspondence proposes a connection
between the Uncertainty Principle on microscopic scales and black holes on
macroscopic scales. This is manifested in a unified expression for the Compton
wavelength and Schwarzschild radius. It is a natural consequence of the
Generalized Uncertainty Principle, which suggests corrections to the
Uncertainty Principle as the energy increases towards the Planck value. It also
entails corrections to the event horizon size as the black hole mass falls to
the Planck value, leading to the concept of a Generalized Event Horizon. One
implication of this is that there could be sub-Planckian black holes with a
size of order their Compton wavelength. Loop quantum gravity suggests the
existence of black holes with precisely this feature. The correspondence leads
to a heuristic derivation of the black hole temperature and suggests how the
Hawking formula is modified in the sub-Planckian regime.
