"Before Christ" (BC) and "Anno Domini" (AD), which translates to "in the year of the Lord," are terms used in the Julian and Gregorian calendars to number years in relation to the traditional, calculated birth year of Jesus of Nazareth, whom Christians believe to be the Messiah.
Here's a breakdown:
* Before Christ (BC): This refers to the years before the traditionally calculated year of Jesus's birth. Years BC are counted backward. For example:
* 100 BC happened 100 years before the traditionally calculated year of Jesus's birth.
* 1 BC is the year immediately before the supposed year of Jesus's birth.
* Anno Domini (AD): This refers to the years after the traditionally calculated year of Jesus's birth. Years AD are counted forward. For example:
* AD 1 is the year traditionally considered the year of Jesus's birth.
* AD 2023 is 2023 years after that year.
Important Considerations:
* Accuracy: It's important to note that the actual historical year of Jesus's birth is debated among scholars. Many believe it was likely a few years earlier than AD 1. The traditional calculation was made in the 6th century by the monk Dionysius Exiguus and is now understood to have been off by several years.
* Zero Year: There is no year zero in this system. The year 1 BC is immediately followed by AD 1.
* Alternatives: Due to the religious connotation of BC and AD, alternative, secular terms are sometimes used:
* BCE (Before Common Era): This replaces BC.
* CE (Common Era): This replaces AD.
The numbering remains the same whether using BC/AD or BCE/CE. So, 100 BC is the same as 100 BCE, and AD 2023 is the same as CE 2023.
In summary, "Before Christ" (BC) and "Anno Domini" (AD) are a dating system based on the traditional, but not necessarily accurate, birth year of Jesus. They are used to chronologically order events in history, with BC indicating years before that birth year and AD indicating years after.