Advent 2021 begins on November 28. Advent begins four Sundays before Christmas and therefore varies in length between 22 days and 28 days. Advent is the beginning of the liturgical year in the Catholic Church. It is a time of preparation for the coming of Christ at Christmas. It was historically known as "little Lent," because, like Lent, it is a time of repentance, with prayer, fasting, and penance.