A report on Calendar era

In chronology and periodization, an epoch or reference epoch is an instant in time chosen as the origin of a particular calendar era.

This calendar era is based on the traditionally reckoned year of the conception or birth of Jesus, AD counting years from the start of this epoch and BC denoting years before the start of the era.

A calendar date is fully specified by the year (numbered according to a calendar era, in this case Anno Domini or Common Era), the month (identified by name or number), and the day of the month (numbered sequentially starting from 1).

Common Era (CE) and Before the Common Era (BCE) are year notations for the Gregorian calendar (and its predecessor, the Julian calendar), the world's most widely used calendar era.

In 537, Justinian required that henceforth the date must include the name of the emperor and his regnal year, in addition to the indiction and the consul, while also allowing the use of local eras.

Anno Mundi (from Latin "in the year of the world"; לבריאת העולם), abbreviated as AM or A.M., or Year After Creation, is a calendar era based on the biblical accounts of the creation of the world and subsequent history.

The world's most widely used calendar era—in which the current year is 2022 AD/CE—is based on the approximate birthdate of Jesus.

The Holocene calendar, also known as the Holocene Era or Human Era (HE), is a year numbering system that adds exactly 10,000 years to the currently dominant (AD/BC or CE/BCE) numbering scheme, placing its first year near the beginning of the Holocene geological epoch and the Neolithic Revolution, when humans shifted from a hunter-gatherer lifestyle to agriculture and fixed settlements.

The Spanish era (Æra Hispanica), sometimes called the era of Caesar, was a calendar era (year numbering system) commonly used in the states of the Iberian Peninsula from the 5th century until the 15th, when it was phased out in favour of the Anno Domini (AD) system.

The Pompeian Era was a calendar era used by Hellenistic cities in Roman Palestine, in particular the cities of the Decapolis.