The Catholic Church calendar is a liturgical calendar that governs the liturgical 12 months, which is the cycle of seasons and feasts that make up the Christian 12 months. The liturgical 12 months begins on the First Sunday of Creation, which is the fourth Sunday earlier than Christmas, and ends on the Solemnity of Christ the King, which is the final Sunday earlier than Creation.
The Catholic Church calendar relies on the Roman calendar, which was launched by Julius Caesar in 46 BC. Nevertheless, the Catholic Church calendar has been modified over the centuries to replicate the Church’s personal historical past and traditions.