The church's liturgical year has a calendar that runs from the beginning of Advent to the Solemnity of Christ the King.

The calendar is set in two parts to account for feasts that change dates (mostly based on the changing date of Easter) and feasts with fixed calendar dates (e.g. Christmas is always on December 25th).

The moveable feasts are laid out in the Temporale. This includes all Sundays.

Feasts with fixed dates (such as Christmas) are set in the Sanctorale.

For a given calendar year, the resulting dates are laid out and published in the Ordo.