This book reviews the mathematical and physical aspects of Black Holes. In particular a Schwarzschild Black Hole was discussed: its singularity aspect, analytical extension of the space-time and Carter-Penrose diagram are explicitly shown. It considers also the effect of electric charge and rotation of the Black Hole. New physical effects that arise due to these two parameters of charge and angular momentum are also discussed. The most interesting aspect of charge and rotation is that time-like singularities deep inside the Black Holes make possible a time travel into new universes. In the Schwarzschild Black Hole case the singularity is space-like and such possibilities do not arise. Finally particle creation by Black Holes due to Hawking is discussed briefly.