AD or CE?

In much of the world today, we use a calendar that has its roots in ancient Egypt, Rome, and medieval Europe.  Adapted by Christian scholars, it uses the year of Jesus' birth as its point of reference:

BC.............Jesus' birth...........AD

Before Christ .......................><...................... Anno Domini *

*(Latin: The Year of Our Lord)

In modern times much of the world has adopted this calendar, but many  persons prefer not  to use the religiously oriented terminology.  Therefore another set of designations has come into use.

BCE................|.................CE

Before the Common Era...................................The Common Era

The correct form for writing Anno Domini dates is A.D. 1243.  All of the other abbreviations go after the year.

In our class use any form you prefer. 

Whichever label you choose, the scale counts outward from its center point, Therefore, the year 150 BCE [or BC] is farther in the past than the year 7 BCE.  This "backward" count may confuse at first, and students of ancient history must always be careful to notice which side of the center point is being used.

"Millennium" is a period of one thousand years.  We have just entered the Third millennium and the Twenty-first century.  I works like this:

Centuries also require a little concentration:  For example, he Declaration of Independence (1776) was written in the Eighteenth century.