In this talk, we will explain and construct the category of quasicoherent sheaves over a general prestack, and we will explain that in certain nice geometric situations the category of quasicoherent sheaves contains all the information about the geometric objects. We will also explain how by passing to quasicoherent sheaves (i.e., going one categorical level up) we will find ourselves in a much more manageable situation. Time permitting we will discuss some applications of this machinery. Speaker(s): Attilio Castano (UM)