Ce year dating
When I was a kid, I was always taught to refer to years using BC (Before Christ) and AD (Anno Domini / year of our Lord). That is, BC is usually understood to mean "Before the Common Era" and CE to mean "Common Era," though it is possible to reinterpret the abbreviations as "Christian Era." The simplest reason for using BCE/CE as opposed to AD/BC is to avoid reference to Christianity and, in particular, to avoid naming Christ as Lord (BC/AD: Before Christ/In the year of our Lord). Marking it as the "Christian Era" (or more commonly, the "Common Era") allows the same epoch to be used even though the best calculation for Jesus's birth has changed.
However, I somewhat regularly hear people referring to years as in the CE (Common Era) or BCE (Before the Common Era). Wikipedia, Anno Domini article: , but a few years earlier (i.e., in the somewhat ironic 3–4 B. While Christians make up a very large chunk of the world's population, they are no where near the majority.
Dates in the Gregorian calendar in the Western world have always used the era designated in English as Anno Domini or Common Era, but over the millennia a wide variety of eras have been used with the Julian calendar. At its core, that date—any date really—is just a code.It's a three-part system allowing those in various locations and points of time to distinguish when an event occurred or will occur. Spoilers: The planet's been around longer than any of us—or any of our ancient relatives—can remember.The first two parts—the month and date—have had a legion of originators, from Cro-Magnon astronomers marking phases of the moon on their eagle bones, to Mayan mystics tracking the movements of the stars from their forest canopies. Tests date the Earth to about 4.54 billion years old, but a whole lot of that time didn't really have anything of substance—to us humans, at least.The 365-and-change-day calendar we use is the result of scientific sweat, an attempt to bring us to a Verifiable Truth regarding how long it takes the Earth to complete one rotation around the sun. Starting a calendar 4.54 billion years ago doesn't make much intuitive sense.