Instead of AD and BC
CE and BCE are used in exactly the same way as the traditional abbreviations AD and BC.
AD is short for Annus(sic) [actually, Anno] Domini,
Latin for year of the Lord.
BC is an abbreviation of Before Christ.
Because AD and BC hold religious (Christian) connotations, many prefer to use the more modern and neutral CE and BCE to indicate if a year is before or after year 1.
https://www.timeanddate.com/calendar/ce-bce-what-do-they-mean.html