Ad dating system
It was invented, more or less, by Dionysus Exiguus (circa 470 – 544).
His fellow monks testify to his character, as one put it, "I can with truth declare that I never saw with my eyes or heard with my ears anyone return thanks so unceasingly to the living God." Bede, for his part, only qualified his reputation as a hard working scholar: "I really don't work 'night and day,' but it is quite true that I do toil hard to reach a right judgment on all that I read." Bede was a renaissance scholar: He wrote on grammar, mathematics, poetry, church music, rhetoric, and science, both for a general audience and for his own pupils. 731, and without it, we would know little of the early centuries of Christianity in Britain, especially the history of Celtic Christianity, early missions to the Continent, and the definitive Synod of Whitby (during which the Celtic church submitted itself to Rome).If the Anno Domini system hadn't been adopted, the United States might refer to the current date as "December 13 of the sixth year of the Obama Presidency", while the British would describe it as "December 13 of the 62nd year of the reign of Elizabeth II".(This answer-comment was originally posted as a comment when the post was locked and no open for questions.) The use of Anno Domini ("in the year of our Lord") was first used in narrative history by Bede (although it had been used very slightly in some annals before that).And, as has been demonstrated above, because the AD/BC system is not actually based upon the birth of Jesus, but is rather off by approximately 7 years, there is no concern from non-Christian peoples to be suspicious of being surreptitiously forced into adopting a dating system based upon the life of is time for Christians to let go of the inaccurate, and to many, offensive BC and AD calendar labels and adopt the BCE/CE system. One interesting side note: Because of a variety of changes and adjustments made to the calendar during the middle ages, it turns out that Jesus was most likely born in what we now think of as 6 B. Even today in Japan there are three different dating systems.
Anno Domini is used now, but there is also an era name based on the current emperor (Heisei 21 is 2009), and there is even an imperial year (currently Kōki 2669) based on the date Japan was supposedly founded by Emperor Jimmu whose historicity, like Jesus’s is questionable.
For example in Rome there were several different ways of giving a year based on such things as the year of the reign of an emperor, who the consuls for the year were, or the number of years from the founding of Rome.
In fact, when Julius Caesar instituted the Julian calendar (which our modern Gregorian calendar is a modified form of) in 45 BC, the year to him was still 709 meaning “from the founding of the City [of Rome]“.
More specifically, the young Bede was given over to the care of the abbot Benedict Biscop, a learned man with refined tastes, who introduced Bede to the world of beauty and scholarship.
Bede's love for church liturgy was cemented during an early tragedy, when all the monks but Benedict succumbed to the plague and Bede and his abbot alone labored together to continue the services until others could be sent to support them.
There is no "zero" year -- in this system, the year Christ was born is 1 A. Russia and Turkey, for example, did not convert to the modern calendar and year scheme until the 20th century.