periodization

In historiography, periodization is the process or study of categorizing the past into discrete, quantified, and named blocks of time for the purpose of study or analysis. This is usually done to understand current and historical processes, and the causality that might have linked those events.

Periodizations can provide a convenient segmentation of time, wherein events within the period might consist of relatively similar characteristics. However, determining the precise beginning and ending of any 'period' is often arbitrary, since it has changed over time and over the course of history. Systems of periodization are more or less arbitrary, yet it provides a framework to help us understand them. Periodizing labels are continually challenged and redefined, but once established, period "brands" are so convenient that many are hard to change.