Black holes

Abstract Black holes are introduced as solutions of Einsteins equations contain-ing a physical singularity covered by an event horizon. The properties of Schwarzschild and of Kerr black holes are examined. It is demonstrated that the event horizon of a black hole can only increase within classical physics. However, the event horizon is an infinite redshift surface and emits in the semi-classical picture thermal radiation. This Hawking radiation leads in turn to the information paradox.