Meaning of terms BC and AD in years

We use these terms a lot, say like the current year, 2007 AD, and the year 50 BC. But what do they mean ?

A.D.--abbreviation for Anno Domini (Latin), "the Year of Our Lord;" in reference to the count of years measured from the birth of Christ, arbitrarily fixed as A.D. 1. Dating by the Annus Domini system was first proposed in 525 and adopted in A.D. 644.

B.C.--abbreviation for "Before Christ," as in 44 B.C. The notation of counting backwards from the birth of Christ was first proposed by Jacques Bossuet in 1681.

It is commonly thought that BC stands for "before Christ" and AD stands for "after death." BC does stand for "before Christ.", but AD actually stands for the Latin phrase "anno domini" which means "in the year of our Lord." The B.C. / A.D. dating system is not taught in the Bible. It actually was not fully implemented and accepted until several centuries after Jesus' death.

It is interesting to note that the purpose of the BC / AD dating system was to make the birth of Jesus Christ the dividing point of world history. However, when the B.C. / A.D. system was being calculated, they actually made a mistake in pinpointing the year of Jesus' birth. Scholars later discovered that Jesus was actually born in around 4-6 BC, not 0 AD.

Any reference to the "Year 0" is also a misnomer. The first year before an occasion (such as the birth of a historical Jesus) would be the year 1 BC. The event would occupy no time (or maybe just one day, depending on your definitions) and the first year after that event would be the year 1 AD. Since the terms were unknown at the occasion itself, there was no problem. ( An archeologist once tried to claim he found a Roman coin dated 3 BC. Think about it.) The confusion over the actual date of the millenium was based on this. Since the first year of the first millenium was the year "0001", the first year of the third millenium was therefore the year "2001". The thousands digit is always one less than the number of the "millenium"; this is the same confusion about the hundreds digit being one less than the "century". 1901 was the first year of the twentieth century, 2001 the first year of the twenty-first century.

Anno domini was invented 525 years after the alleged birth of Jesus; The Anno Domini system was developed by a monk named Dionysius Exiguus (born in Scythia Minor) in Rome in 525, as an outcome of his work on calculating the date of Easter.... http://en.wikipedia.org/wiki/Anno_domini..