The Catholic Calendar
The Roman Catholic Calendar is used to mark the various important days in the Catholic faith and the days that they are to be observed. It should be noted that the Catholic calendar, is not a unique calendar system, it instead is used in accordance with the traditional western calendar. The calendar is intended to maintain standardized religious events in the various areas where the Catholic faith is practiced. Within the calendar there are some events that must be observed on a fixed date, and others that are considered moveable in relation to the date of Easter on that particular year; these dates are called "moveable."
A large part of the Catholic calendar is based on Easter. Easter is declared to be the first Sunday after the first full moon that occurs after March 20th of a particular year. Once this date has been set, other important Catholic events fall into place. This includes Ash Wednesday and Good Friday before Easter and The Feast of Divine Mercy and Ascension of the Lord after Easter. There are however, five days that are not moveable and are known as Holy Days of Obligation. These days include Ascension (June 2), Assumption of Mary (August 15), All Saints Day (November 1), Immaculate Conception (December 8) and Christmas (December 25).