What Is Time?

In this paper, I answer the question of what time is. First, however, I consider why one might ask this question and what exactly it is asking. The latter consideration reveals that in order to answer the question, one must first engage in a more basic investigation of what a thing, anything at all, is. Such radical investigation requires a special methodology. After briefly characterizing this methodology, I show how it can be employed to answer the titular question. This answer is significant not merely because it illuminates something of perennial interest, but because it is essential to a comprehensive and fully satisfactory metaphysics of time and, hence, to a view of the full structure in reality.