The Anno Domini dating system was devised in 525 by Dionysius Exiguus to enumerate the years in his Easter table.
His system was to replace the Diocletian era that had been used in an old Easter table because he did not wish to continue the memory of a tyrant who persecuted Christians.
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).
The word “Common” in both instances refers to the date employed by the most commonly used calendar system, the Gregorian Calendar.
The years are the same, only the designations are different.
It was not actually developed until 525 AD, when the entrance of the Christ into the world was recognized as being the turning point of history, and our calendars were made to reflect that.3 In regard to the use of BCE and CE, these are more recent developments.
In most usages, BCE stands for “Before the Common Era,” and CE stands for “Common Era.” BCE is used in place of BC, and CE is used in place of AD.
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.
Thus Dionysius implied that Jesus' Incarnation occurred 525 years earlier, without stating the specific year during which his birth or conception occurred.
"However, nowhere in his exposition of his table does Dionysius relate his epoch to any other dating system, whether consulate, Olympiad, year of the world, or regnal year of Augustus; much less does he explain or justify the underlying date." It is not known how Dionysius established the year of Jesus's birth.
However, BC is placed after the year number (for example: AD 2017, but 68 BC), which also preserves syntactic order.