A notation used to specify years in the current numbering system. Years prior to 1 AD are denoted BC or BCE.Note that 1 BC immediately precedes 1 AD;there is no year 0. AD stands for "anno Domini," Latin for "year of our Lord." The notation CE ("Common Era") is sometimes used instead of AD.
Although the Roman abbot Dionysius Exiguus proposed that the years be numbered from the birth of Christ in about 524 (Boyer 1968, p. 272), Bede was the first to actually date events from the birth of Christ. This system gives rise to the familiar classification of dates as BC or AD (also sometimes denoted BCE and CE).
Interestingly enough, probably because the concept for zero was not widely used in Europe at the time, this method of dating omits the year zero, so that the year 1 BC is followed immediately by the year 1 AD. This fact leads to periodic disputes concerning the beginning of "new" millennia and centuries.In any case, whoever zeroed the calendar made an error, since the Bible says Jesus was alive in Herod's time, but Roman records showed that Herod died in what turns out to be 4 BC.