Common Era (CE; Latin: aera vulgaris) is a method used to identify a year. It means "a year in our time" (rather than a year a very long time ago). It is the system for recording dates used almost everywhere around the world today. It is in common use.
CE is an alternative to the AD system used by Christians but the numbering is the same: the year 2023 CE is equally AD 2023 (but usually we just say "the year is 2023"). AD is an abbreviation of the Latin: anno domini, lit. 'year of the lord'. The CE method was created as an alternative to AD as not everyone is a Christian. However, the name Christian Era (Latin: aera christiana) is another name for Common Era.
When writing about calendars, an era is span of dates, starting from a particular moment in time. In the case of both CE and AD, that start date is approximately the date of the birth of Jesus of Nazareth. Neither system uses a year zero (0): the year before 1 CE was 1 BCE.
Before Common Era change
Before Common Era (BCE) is the system for the years "Before the Common Era". BCE uses the same numbering as BC (Before Christ). "CE" and "BCE" are placed before the year number. Thus we write "Right now our year is 2023 CE" or "Artaxerxes III of Persia was born in 425 BCE."
Usage of Common Era notation began about 1615 among Christians in Europe, and has been growing among non-Christians and among Christians who desire to be sensitive to non-Christians.