CE stands for "Common Era," while BCE stands for "Before the Common Era". These abbreviations are used as year notations for the Gregorian calendar, which is the worlds most widely used calendar era. They are secular alternatives to the traditional BC and AD, which reference Christs birth directly. The use of BCE/CE has become more widespread in the later part of the 20th century, replacing BC/AD in a number of fields, notably science and academia. BCE/CE is also considered a more inclusive and secular way to say AD. BCE and CE both refer to years after the birth of Jesus Christ, but they remove the explicit reference to Christ. The choice of which notation to use is up to the writer, but they should use their chosen system consistently.