We can portray or take on the role of someone whom we are not. For example, a professional actor can play the role of a fictional character who does not exist in the real world, although she believes she is not that person. This behavior is named “acting.” My aim here is to locate the necessary and sufficient conditions of acting. In my view, acting is a process of communication between actors and audiences. One of its necessary components is that (...) actors use their own features to represent those features that their characters have; another is that actors intend to make their audiences imagine that they are themselves identical to their characters. In this article, I specify these two components, critique other views of the definition of acting and distinguish acting from other similar processes. (shrink)