Formula One, abbreviated to F1, is currently the highest class of open-wheeled auto racing defined by the Fédération Internationale de l'Automobile (FIA), motorsport's world governing body. The "formula" in the name refers to a set of rules to which all participants and vehicles must conform. The F1 World Championship season consists of a series of races, known as Grands Prix, usually held on purpose-built circuits, and in a few cases on closed city streets. The results of each race are combined to determine two annual championships, one for drivers (World Drivers' Championship), and one for constructors (World Constructors' Championship).This list is for the circuits that hosted World Championship races from 1950 until now. The terms "Formula One race" and "World Championship race" were not always synonymous throughout history – see Formula One#Distinction between Formula One and World Championship races for a detailed explanation.