The layers that build up the notion of time

Abstract: Confusion and disagreement around the notion of time is due to the fact that we often fail to recognize that we call 'time' a variety of distinct notions, only partially related to one another. Many apparently obvious properties of time are results of different kinds of approximations, idealizations, or special contexts. I illustrate a number of distinct notions of time, their differences and relations; they are all relevant for describing the real world. To understand time, we have to break it apart.