Each year has a number. To tell the date of a happening, we give the number of the year. We say, for instance, that Columbus discovered America in 1492.
The years are numbered from the year that was supposed to be the one in which Christ was born. To give the date of earlier happenings, we count back from the year I. We then put B.C. after the number. B.C" stands for "before Christ." The dates of happenings after the birth of Christ sometimes have A.D. before the number. The initials "A.D." stand for the Latin words anno Domini. These words mean "in the year of our Lord."
A.D. I was not actually the year when Christ was born. A mistake was made. Christ was born at least four years earlier. But when the mistake was discovered, it was too late to change the calendar.
Our way of numbering years did not begin till several hundred years after Christ died. Before then there were other ways of telling the date.
The Romans counted their years from the date of the founding of Rome. The Greeks counted their years from the date of the first Olympic games.
In still earlier times years were often named instead of numbered. Another plan was to number the years in a ruler's reign. In the Bible one date is "in the first year of Cyrus, king of Persia." "In the fourth year of Solomon's reign over Israel" is a Bible date, too. How well we would have to know lists of rulers if we now had dates like these!
