Common era dating system
(In that system, "AD" stood for Anno Diocletiani, and should not be confused with the present-day AD system.) Because Dionysius Exiguus in the year 525 wanted to end the memorialization of an evil man who persecuted Christians, he invented a new numbering system based on his calculations of the birth year of Jesus Christ.
However, as he miscalculated, the terms BCE/CE are more accurate than BC/AD as the last few years BC were not actually Before Christ, and hence 1 AD is not actually the first year after Jesus' birth.
For instance, in the date AD 2001, the prefix "AD" stands for "Anno Domini" which is Latin for "the year of our Lord." Similarly, in the date 500 BC, the suffix "BC" stands for "Before Christ." In sixth century Europe, the concept of "zero" was still unknown. Furthermore, modern scholars believe Christ's birth was actually four years earlier than Exiguus thought.
In spite of these deficiencies, the dating system devised by Exiguus is now too deeply ensconced in the Western world to easily change.
It should be noted that if multilateral trade deals would have continued to be the norm then the CE mark would have been required to sell goods and services globally.Perhaps the most unfortunately characteristic of this convention is that "BC" is a suffix (used after the year) while "AD" is a prefix (used before the year).