The terms anno Domini[a][1][2] (AD) and before Christ[b][3][4][5] (BC) are used to label or number years in the Julian and Gregorian calendars. The term anno Domini is Medieval Latin and means "in the year of the Lord",[6]but is often presented using "our Lord" instead of "the Lord",[7][8] taken from the full original phrase "anno Domini nostri Jesu Christi", which translates to "in the year of our Lord Jesus Christ".
This calendar era is based on the traditionally reckoned year of the conception or birth of Jesus of Nazareth, with AD counting years from the start of this epoch, and BC denoting years before the start of the era. There is no year zero in this scheme, so the year AD 1 immediately follows the year 1 BC. This dating system was devised in 525 by Dionysius Exiguus of Scythia Minor, but was not widely used until after 800.[9][10]
The Gregorian calendar is the most widely used calendar in the world today. For decades, it has been the unofficial global standard, adopted in the pragmatic interests of international communication, transportation, and commercial integration, and recognized by international institutions such as the United Nations.[11]
Traditionally, English followed Latin usage by placing the "AD" abbreviation before the year number.[c] However, BC is placed after the year number (for example: AD 2018, but 68 BC), which also preserves syntactic order. The abbreviation is also widely used after the number of a century or millennium, as in "fourth century AD" or "second millennium AD" (although conservative usage formerly rejected such expressions).[13] Because BC is the English abbreviation for Before Christ, it is sometimes incorrectly concluded that AD means After Death, i.e., after the death of Jesus. However, this would mean that the approximate 33 years commonly associated with the life of Jesus would neither be included in the BC nor the AD time scales.[14]
Terminology that is viewed by some as being more neutral and inclusive of non-Christian people is to call this the Current or Common Era (abbreviated as CE), with the preceding years referred to as Before the Common or Current Era (BCE). Astronomical year numbering and ISO 8601 avoid words or abbreviations related to Christianity, but use the same numbers for AD years.
That is a picture of Hagia Sophia located in Istanbul, Turkey. The Hagia Sophia served as a center for religious, political, and artistic life for the Byzantine Empire (Eastern Roman Empire). It started as a place of great importance for the Byzantines, but then became a extremely important site of worship when Sultan Mehmed II conquered Constantinople. (Constantinople is modern day Istanbul)
The Forbidden City<span> was the Chinese imperial palace from the Ming dynasty to the end of the Qing dynasty—the years 1420 to 1912. It is located in the center of Beijing, China, and now houses the Palace Museum.</span>