When reading history books, you’ll likely come across the terms BC and AD with a year. Sometimes they’re swapped out for BCE and CE. What exactly do these terms mean, and why are there two versions? I’m here to break it down for you and clear up any confusion.
BCE/CE and BC/AD are dating systems that count years.
- BCE stands for Before the Common Era, and CE stands for Common Era.
- BC stands for Before Christ, and AD stands for Anno Domini, Latin for “the year of the Lord.” The Lord in question is, of course, Jesus Christ.
While the abbreviations stand for different terms, they refer to the same year. With this logic, BCE = BC and CE = AD.
Here are a couple of examples:
- The year 2024 is written as 2024 CE or AD 2024. AD appears before the year.
- The date the ancient Egyptians built the Sphinx is written as circa 2500 BCE or 2500 BC.
Both are correct and mean the same thing! So why the hell are there two systems?
What are BC and AD?
BC/AD counts years from the birth of Jesus Christ, which is AD 1 according to this system. The years after his birth are AD, or “Anno Domini,” and anything before is BC, or “Before Christ.” All BC dates are counted backward from AD 1, so larger numbers are older and occurred before smaller ones. For example, 500 BC came before 20 BC.
Origins
The Christian monk Dionysius Exiguus of Scythia Minor devised the system in AD 525 when he tried to figure out the date for Easter. He messed up, though, and miscalculated Jesus’ birth as AD 1. Historians today believe Jesus was born between 6 BC and 4 BC, so Dionysius was off by a few years.
Nevertheless, his new way of marking years gained traction, especially because it replaced the Diocletian System. Diocletian was a Roman Emperor from AD 284 to 305. Like other emperors, he decided to mark time according to his reign. The ego on this guy. Diocletian also persecuted Christians during his rule, so Dionysius, a monk, said fuck this guy, new system with the Christian God as a starting point.
The term BC came into the equation years later in AD 731, when Venerable Bede of Northumbria published his book, “Ecclesiastical History of the English People.” While the term appeared in earlier publications, this book popularized “BC” and set it on the map.
Charlemagne, King of the Franks and Lombards and Holy Roman Emperor in the 8th–9th centuries, adopted the system, making it even more widespread in Christian Europe. By the 15th century, it was everywhere.
Year Zero?
You might be wondering if there is a year 0 since AD 1 is the starting year of this system. Nope, there isn’t because the concept of “0” wasn’t a thing in Europe during Dionysius’ or Bede’s times. Therefore, we jump from 1 BC to AD 1.
What are BCE and CE?
BCE/CE also uses the year 1 (and skips 0), but labels it CE, or “Common Era,” rather than the birth of Christ, which we know is wrong anyway. With this system, years before 1 CE are labeled BCE, the abbreviation for Before the Common Era. Everything after year 1 is labeled CE, aka Common Era. The first use of “Common Era” dates back to 18th-century England and was often used synonymously with the term “Vulgar Era.” I don’t know about you, but I’m always in my vulgar era.
Back then, though, the term vulgar meant ordinary and common, not crude. “Vulgar Era” first appeared in a 1615 book by German astronomer and mathematician Johannes Kepler. In the past 30-ish years, BCE and CE have become more common in education and scholarship because they’re deemed more accurate and inclusive due to their non-Christian nature.
Okay, so which one, BCE/CE or BC/AD?
I use BCE/CE in my writing because it is more inclusive, and it’s what I learned in grad school, so it’s a habit. You do you and use whichever one you want – remember, they both refer to the same years!
If you found this helpful, check out more “WTF is…” blog posts and subscribe to my email newsletter.
Bibliography & Further Reading
*The first link (Bede) is an Amazon affiliate link, which means I earn a commission if you make a purchase, at no cost to you.
Bede. Ecclesiastical History of the English People (Penguin Classics). Revised ed. Edited by Ronald Latham. Translated by Leo Sherley-Price. Penguin Classics, 1991.
Coolman, Robert, and Owen Jarus. “Keeping Time: The Origin of B.C. and A.D.” Live Science. January 14, 2022. https://www.livescience.com/45510-anno-domini.html
Mark, Joshua J. “The Origin & History of the BCE/CE Dating System.” World History Encyclopedia. Last modified March 27, 2017. https://www.worldhistory.org/article/1041/the-origin–history-of-the-bcece-dating-system/
Leave a Reply