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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. 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. (see also: period)

• 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 timescaleA timeline of geologic periods in accordance with the dates and nomenclature proposed by the International Commission on Stratigraphy. The Earth is thought by geologists to be 4. 6 billion years old. The geologic or "deep" time of Earth's past has been or for a slightly different interpretation and details.
• A calendar eraCalendar era In a calendar, the era is the date from which years in the calendar are counted. For example, in the Gregorian calendar, dates are measured from the beginning of the Christian era. There are many different calendar era systems. Some are liste is the date from which yearA year is the time between two recurrences of an event related to the orbit of the Earth around the Sun. By extension, this can be applied to any planet: for example, "Martian year". Seasonal year A seasonal year is the time between successive recurrencess in the calendarCalendars A calendar is a system for assigning calendar dates to days. The dates may be based on the perceived motion of astronomical objects. A calendar is also a physical device (often paper) that illustrates the system (for example, a desktop calendar are counted.