When reading informative articles, you may occasionally notice jargon that is difficult to decipher for the casual reader. Most specialties have their own acronyms, abbreviations and shorthands which, while they do save time and space, are not always known to the general public. Although most people are familliar with traditional western dating systems, those from other cultures who use different dating techniques or frames of reference may be confused by the notations found in scientific or historical documents.
This article is a brief overview of the traditional western method of keeping track of dates over long spans of time, which will increase your understanding of the chronology of historical events if you find them dated by this method.
This method of dating was first used a few hundred years after the birth of Christ, when a monk was trying to figure out exactly when Christ was born. He based the calendar on the year in which he believed Christ was born, and called that year 1 A.D. A.D. stands for Anno Domini, a Latin term meaning "after Christ." Although scholars now do not believe that Christ was actually born in that year, (but within a few years of that year) the method of dating still stands. Any time you see A.D. before or after a number, it indicates that many years have passed since the birth of Christ. So A.D. 2010, or 2010 A.D. both mean that were are in the two-thousandth and tenth year after Christ's birth.
In contrast, to indicate when an event happened before the birth of Christ, the abbreviation B.C. is used. It is not generally known when this term came into use, but as the letters stand for "Before Christ", an English, rather than Latin, phrase, we can assume that this abbreviation came into use much later than A.D. Dates with a "B.C." indicate the number of years before Christ's birth: 400 B.C. or B.C. 400 indicates an event 400 years before the birth of Christ. Note that, just as with negative numbers, a higher number B.C. actually indicates a lower (farther in the past) value, even though a higher number A.D. indicates a higher (more recent) value.
Before B.C. came into use, E.V, standing for "Era Vulgaris", Latin for "Common Era" was occasionally used.
In recent times, in deference to the fact that western countries are multi-cultural societies in which not everybody worships Christ, the terms B.C.E. and C.E. have come into use. B.C.E. stands for "Before Common Era" and is the equivalent of the old B.C, and C.E. stands for "Common Era," which replaces the old A.D. As these are currently considered the proper and correct notations, you will likely see these in any new papers or articles published, while older dating schemes are found in older papers.
Although the variety of dating systems that have been used can be confusing, this article should help clear the air and help you get more out of the historical articles you're reading.