Black Hole in ADS and Quantum Field Theory

I will present a short review of recent achievements in understanding the origin of the statistical properties versus the thermodynamical ones for Anti De Sitter space--time, ADS$_{n+1}$ from the point of view of the "dual" field theory defined on the boundary of ADS$_{{n+1}}$ conformal invariant, CFT$_n$. We try to convince the audience that the symmetries of Quantum Field Theory at the critical points are, on one side, at the basis of the thermodynamical properties of Black Hole solution, i.e. the Hawking temperature $T_H$ and the entropy $S_H$; on the other side the CFT$_n$ in Euclidean time determines the statistical properties of BH.