Common Era (CE) is one of the year notations used for the Gregorian calendar, the world's most widely used calendar era. Before the Common Era (BCE) is the era before CE. BCE and CE are alternatives to the Dionysian BC and AD notations, respectively. The Dionysian era distinguishes eras using the notations BC and AD. The two notation systems are numerically equivalent: "2021 CE" and "AD 2021" each describe the current year; "400 BCE" and "400 BC" are each the same year. The Gregorian calendar is used throughout the world today, and is an international standard for civil calendars.
