The centrality of the concept of time within Heidegger's thinking is beyond dispute. From early Marburg investigations such as the 1924 essay “The Concept of Time” to late works such as the 1962 “On Time and Being,” Heidegger attempts to uncover the ontological nature of temporality, and, in particular, the relationship, as he understands it, between time and being. In Being and Time, by far his most influential study of time, he announces in the introduction that “the meaning of the Being of that entity which we call ‘Dasein’” will be temporality. The fundamental intelligibility of Dasein's (that is, the entity that we are in so far as our own being, as Heidegger puts it, is an issue for us) existence is made possible by a deep transcendental level which is alternately referred to as “ecstatic” or “original” temporality, and which must be sharply distinguished from “vulgar” time, the quantitative time of clocks and objective measurement.

Heidegger's theory of time, especially in Being and Time, has generated a huge body of scholarship. By picking up and developing Augustine's claim against Aristotle that time must be understood not as the succession of irreversible and homogeneous now-points but as man's (or Dasein's) fundamental manner of being, Heidegger renews the post-Kantian discourse of time and gives it a decisive twist towards what he calls “the how” of Dasein.