Conventional wisdom dictates that B.C. and A.D. relate to the birth of Jesus Christ.
B.C. = Before Christ
A.D. = Anno Domini (In the year of the Lord).
However careful examination of scripture produces some discrepancy:
So according to the Bible as cross-referenced with all known historical documents, Jesus was born between 4 A.D. and 6 A.D., and not 1 A.D.
Nowadays, most respected scientists and others in the scientific and historical community use a different nomenclature when referring to ancient dates:
B.C.E. = Before Common Era
C.E. = Common Era
1 A.D. = 1 C.E.
1 B.C. = 1 B.C.E.
The periods related to the same dates in time but in order to not pander to one particular religion over any other, a more uniform naming convention is used in science and other areas.
Last updated by Nelson Feb 12, 2009.