The word Advent is from the Latin adventus for "coming" and is associated with the four weeks of preparation for Christmas. Advent always contains four Sundays, beginning on the Sunday nearest the feast of St. Andrew the Apostle (November 30) and continuing until December 24.
In 2023, Advent begins on December 3 and ends on December 24 (Christmas Eve), as the Mass of the Lord’s Nativity begins. Christmas Day is December 25. (Source: EWTN)