Periodization is the process or study of categorizing the past into discrete, quantified named blocks of time in order to facilitate the study and analysis of history. This results in descriptive abstractions that provide convenient terms for periods of time with relatively stable characteristics. However, determining the precise beginning and ending to any "period" is often arbitrary.

To the extent that history is continuous and ungeneralizable, all systems of periodization are more or less arbitrary. Yet without named periods, however clumsy or imprecise, past time would be nothing more than scattered events without a framework to help us understand them. Nations, cultures, families, and even individuals, each with their different remembered histories, are constantly engaged in imposing overlapping, often unsystematized, schemes of temporal periodization; periodizing labels are continually challenged and redefined, but once established, a period "brand" is so convenient that many are very hard to shake off.

Periodization may refer to: