This paper deals with A.N. Prior's analysis of the concepts of dynamic and static time, i.e. McTaggart's so-called A- and B-concepts. The relations and mutual dependencies between these temporal concepts are investigated, and Prior's response to McTaggart's views is discussed. Futhermore, Prior's notion of branching time is analysed. It is argued that Prior can be criticized for identifying 'plain future'. Finally, Prior's four grades of tense-logical involvement are introduced and discussed. It is argued that the third grade is the most attractive form a philosophical point of view.