Anno Domini It's Latin and translates to 'in the year of our Lord'. It's used talk about the years since the birth of Jesus.

As others have said, "AD" or "A.D." can mean the traditional calendar era system that traces back to Christianity in Europe. It is part of a pair, "AD" and "BC" for "anno domini" and "before Christ." For example, this year is the year 2015 AD. Usually of course we just called it 2015. The ancient Roman emperor Julius Caesar died in the year 44 BC. In modern scholarly work, it is customary to use a different pair of abbreviations: CE, for "common era," instead of AD, and BCE, "before common era," for BC. They are used because they are more neutral in religion and more respectful of non-Christians. "Common era" reflects the neutral fact that this is the most widely used calendar era. Ironically, the scholars who created the designations AD and BC were slightly off in their chronology, and scholar generally think that that Jesus of Nazareth, founder of Christianity, was actually born in or about the year 4 BC. AD is usually seen in formal inscriptions, particularly when carved in stone, commemorating historic events. For example, in the United States, tombstones in cemeteries will often give the dates of birth and death using the term "AD." When referring to historical events, BC and AD will often be used if the dates are close enough to the start of the era that there could be doubt. We would say that the United States was founded in 1776, not 1776 AD. However, if someone referred to "the year 422," one might say "is that AD or BC?"

abbreviation for Anno Domini ( These are Latin words used to refer to years after birth of Christ )

Remember the simple question form! :) "What does AD refer to?" "What does AD mean?" or "What does AD stand for?"(ie. the word for each letter.)

a year always come after it like 100 AD