BCE meaning in Measurement Unit ?

Common Era (CE) is one of the year notations used for the Gregorian calendar (and its predecessor, the Julian calendar), the world's most widely used calendar era. Before the Common Era (BCE) is the era before CE. BCE and CE are alternatives to the Dionysian BC and AD notations, respectively. The Dionysian era distinguishes eras using the notations BC ("Before Christ") and AD (Latin: Anno Domini, in [the] year of [the] Lord). The two notation systems are numerically equivalent: "2021 CE" and "AD 2021" each describe the current year; "400 BCE" and "400 BC" are each the same year. The Gregorian calendar is used throughout the world today, and is an international standard for civil calendars.

The expression has been traced back to 1615, when it first appeared in a book by Johannes Kepler as the Latin: annus aerae nostrae vulgaris (year of our common era), and to 1635 in English as "Vulgar Era". The term "Common Era" can be found in English as early as 1708, and became more widely used in the mid-19th century by Jewish religious scholars. Since the later 20th century, CE and BCE are popular in academic and scientific publications as religiously neutral terms. They are used by others who wish to be sensitive to non-Christians by not explicitly referring to Jesus as "Christ" nor as Dominus ("Lord") through use of the other abbreviations.