Final answer:
Dionysius Exiguus, a Christian monk, introduced AD and BC in the 6th century for dating events from Christ's birth, later replaced by BCE and CE for secular use.
Step-by-step explanation:
The practice of dating events from the birth of Christ was introduced by Dionysius Exiguus, a Christian monk, in the 6th century. He established the terms Anno Domini (AD) and Before Christ (BC) to mark the years in the Julian calendar. Later, to provide a non-religious alternative, the terms Before the Common Era (BCE) and Common Era (CE) were adopted in academia and scientific communities for broader secular and inclusive use without specific religious connotation. This system is still commonly used today, although there is also a scholarly alternative known as Before the Common Era (BCE) and Common Era (CE) that is used by academic and scientific publications to emphasize secularism and inclusiveness.