The liturgical year for us, as Catholics (and some other Christians as well) begins on the First Sunday of Advent and goes through the year to end on the Feast of Christ the King.
The Liturgical Seasons of the Church are:
Advent Season
The liturgical year begins on the First Sunday of Advent. This is the season of preparation for Christ’s Birth. Sometimes called a “little Lent,” Advent is a period of joyful expectation but also of penance. In the Roman Rite of the Catholic Church, Advent begins with First Vespers (Evening Prayer I) of the Sunday that falls on or closest to November 30 and it ends before First Vespers (Evening Prayer I) of Christmas.
Christmas Season
Christmas season in the liturgical calendar is actually called Christmastide. It begins on December 25 and ends on the Sunday after January 6, the Sunday celebrating the Baptism of the Lord, a period of about 20 days, depending upon the year.
Before the Second Vatican Council, the Christmas season lasted 40 days, replicating the 40 days of Lent. The liturgical calendar of the Extraordinary Form of the Mass (the Latin Mass) still celebrates an extended Christmas, lasting until February 2nd, the Feast of the Presentation of the Lord.
Ordinary Time
A rather misleading term, in our opinion, Ordinary Time is a time for growth and maturation.
Lent
Lent is a period 40 days, not including Sundays…which means that it is actually 46 days long. Similar to advent, it is a season of preparation: prayer, fasting, and alms-giving, beginning on Ash Wednesday and ending at sundown on Holy Thursday.
Easter Season
Also known as “Eastertide”, the Easter Season lasts for 50 days, culminating with the feast of Pentecost.
Easter Triduum
The Easter Triduum actually marks the end of the season of Lent. As the name implies, it consists of only three days:
The First Day: Holy Thursday
The Second Day: Good Friday
The Third Day: Holy Saturday
Ordinary Time again, ending on the feast of Christ the King, the last Sunday before Advent. This is the last Sunday of the liturgical year.
