Períodes

Períodes are units used to mark spans of time or phases in different disciplines. They provide a framework for describing when events occur, how processes unfold, and how patterns repeat. The concept appears in geology, history, linguistics, and the natural sciences, and the definition of a period can vary by context.

In geology, a period is a subdivision of an era on the geologic time scale, typically lasting millions of years. It sits between eras and epochs in the hierarchy of time. Well-known periods include the Cambrian, Jurassic, and Cretaceous, among many others in the Paleozoic, Mesozoic, and Cenozoic.

In history and cultural studies, periods denote phases defined by distinctive social, political, or artistic features. Examples range from the Middle Ages and the Renaissance to the Industrial Age. Regional differences and scholarly debates can shift the dating and naming of these periods.

In science and writing, a period can also mean the duration of a repeating cycle—such as a pendulum’s period or a circadian rhythm—or the punctuation mark that ends a sentence (the full stop in British usage). The plural form is periods.

Originates from Greek periodos via Latin periodus, meaning a going around or circuit.