Science Fair Project Encyclopedia
See also: ERA (disambiguation page).
An era is a (usually lengthy) period of time with common characteristics. For example: the Biblical era, the Roman era, the Elizabethan era, the Victorian era and the Soviet era. The word period is used interchangably with era in this context. Era is also popularly used to denote the passing of shorter periods, such as the Big Band era, Disco era. Something like the death of Frank Sinatra is called the end of an era.
- In Geology, era refers to four well defined time spans covering the history of the Earth. From oldest to youngest, these are the Proterozoic, Paleozoic, Mesozoic, and Cenozoic eras. See Geologic timescale for a slightly different interpretation and details.
- A calendar era is the year numbering system used with a calendar.
- In music, see musical eras, described in History of music.
Eras in World Cultures
Era was an East Asian imperial practice of numbering years in an emperor's reign. It originated as a motto or slogan chosen by the emperor. Different East Asian countries utilized slightly different systems:
A similar practice has happened in the United Kingdom until quite recently. Acts of Parliament used to be dated according to the years of the reign of the current Monarch, so that "61 & 62 Vict c. 37" refers to the Local Government (Ireland) Act 1898 passed in the session of Parliament in the 61st/62nd year of Queen Victoria.
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