Periodization is the process or study of categorizing the past into discrete, quantified named blocks of time.[1] This is usually done in order to facilitate the study and analysis of history, understanding current and historical processes, and causality that might have linked those events.

Petrarch conceived of the idea of a European "Dark Age" which later evolved into the tripartite periodization of Western history into Ancient, Post-classical and Modern.

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, since it has changed over time over the course of history.

To the extent that history is continuous and not generalized, 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 schemes of temporal periodization. Periodizing labels are continually challenged and redefined, but once established, a period "brand" is so convenient that many are hard to change or shake off.