1. B.C. and A.D.

2. Timelines B.C. stands for Before Christ.
It means the number of years before the time of Jesus Christ.
Some people use B.C.E. instead

3. B.C.
It stands for Before the Common Era, and is used in order to avoid Christian references.
However, the dating system is a Christian system.
The dates in B.C. run backwards from year 1.

4. Timelines
A.D. stands for Anno Domini, which is Latin for “year of our Lord,” and it means the number of years since the time of Jesus Christ.
Some people use C.E. instead. This stands for Common Era and people use it to avoid Christian references.

5. A.D.
There are other non Christian dating systems in the world, but the most widely recognized is B.C. and A.D.

6. The calendar as we know it in our western world was created in the 16th century. It was first proposed by Aloysius Lilius and requested by the Pope Gregory XIII, after whom it was named, we call it a Gregorian Calendar. Latin was the language used in the church thus AD Anno Domini(Medieval Latin: In the year of (the/Our) Lord), It was actually Anno Domini Nostri Iesu Christi meaning In the Year of Our Lord Jesus Christ. B.C. is the English abbreviation for Before Christ, some people incorrectly conclude that A.D. must mean After Death. However, if we were to use AD as after death it would mean that 33 years would be missing from each calendar...

7. Comparing B.C. and A.D. Dates
There was no year 0; that forces us to make an adjustment when we compare A.D. and B.C. dates.
You could find the time from, say, 5 B.C. to 7 A.D. by subtracting a negative number: or = ? Years.
But, our timeline contains a 0!!!!!!