Marginally outer trapped surfaces as quasi-local black holes
Marginally outer trapped surfaces (MOTS) are generally believed to be suitablequasi-local replacements for the concept of black hole. In this talk I willdiscuss a number or rigorous results obtained in the last few years that put thisexpectation on firmer grounds. Specifically, I intend to mention existence of MOTS in an initial data set, smooth local evolution of MOTS, jumps of outermost MOTS, the Penrose inequality conjecture and uniqueness theorems of static spacetimes containing a MOTS.