Critical behavior in black hole thermodynamics

In this talk I introduce the critical behavior occurring at the extremal li mit of black holes. The extremal limit of black holes is a critical point a nd a phase transition takes place from the extremal black holes to their no nextremal counterparts. Some critical exponents satisfying the scaling laws are obtained. From the scaling laws we introduce the concept of the effect ive dimension of black holes and discuss the relationship between the criti cal behavior and the statistical interpretation of black hole entropy.