Q. 1. What is the meaning of A.D. and B.C.?
A. 1. B.C. is the term used for events in history that occurred "Before Christ." A.D. is the term used for events in history that occurred "After Death" of Christ. It stands for "Anno Domini," such being Latin for the "Year of the Lord."
The A.D. era is referred to as the Gregorian calendar, named after Pope Gregory VIII. The B.C. (Before Christ) era is referred to as the Julian calendar, based on the approximate year of the Incarnation.
So 500 B.C. is a reference to 500 years before Christ. 500 A.D. is a reference eto 500 years after Christ.