The liturgical year serves as the Catholic Liturgical Calendar. It consists of the cycle of liturgical seasons that determine when feast days and other holy days are observed, and which Scripture and Gospel readings are used at Mass.
Aside from the readings, the Liturgical Calendar also determines the interior decoration of a Church, the priest's vestment colors, the timing of spiritual seasons and practices such as Lent, and much more.
The Liturgical calendar year begins on the first Sunday of Advent. It is divided into six seasons. The shortest but most holy season is the three day Sacred Pascal Triduum leading up to Easter.
The last Sunday of the liturgical year is the Solemnity of Jesus, King of the Universe. We begin the new year on Dec. 1st, the first Sunday of Advent. With the new year, we hear readings from Cycle A, which will include the gospel of Matthew.