AD? BC? BP? What Letters After Years Mean

On January 1, 1950, a new method of designating what year it is (or was) went into effect with the BP system, meaning “Before Present.” The Anno Domini (“the year of our Lord”) choice of a starting date for modern counting of years was proposed by the colorfully named Dionysius Exiguous (a monk from what is now modern Bulgaria or Romania) back in 525 AD. (Yes, you can use the letters with or without the periods.)