A chronon is a proposed quantum of time, that is, a discrete and indivisible "unit" of time as part of a hypothesis that proposes that time is not continuous.

In simple language, a chronon is the smallest, discrete, non-decomposable unit of time in a temporal data model. In a one-dimensional model, a chronon is a time interval or period, while in an n-dimensional model it is a non-decomposable region in n-dimensional time. Important special types of chronons include valid-time, transaction-time, and bitemporal chronons. It is not easy to see how it could possibly be recast so as to postulate only a discrete spacetime (or even a merely dense one). For a set of instants to be dense, there must be an instant between any two instants. For it to be a continuum, however, something more is required—viz., that every set of instants earlier (later) than any given one should have an upper (lower) bound. It is continuity that enables modern mathematics to surmount the paradox of extension framed by the pre-Socratic eleatic Zeno—a paradox comprising the question of how a finite interval can be made up of dimensionless points or instants.