The Christian calendar is marked by the seasons that lead us through the birth, life, death, resurrection, and ascension of Jesus Christ. These seasons do not necessarily occur on the same dates from year to year, but are related to the dates of Christmas and Easter.
Advent season begins four Sundays before Christmas.
The Christmas Season includes the twelve days from sunset on Christmas Eve (December 24) through Epiphany (January 6).
The Season After Epiphany begins January 7 and lasts until Ash Wednesday.
Lent begins on Ash Wednesday and lasts until Easter. The exact dates of Lent depends on the date for Easter Sunday.
Easter is the first Sunday after the first full moon after March 21. Easter moves between March 22 and April 25. The Easter Season is fifty days long and goes through the Day of Pentecost.
The Season After Pentecost begins immediately after Pentecost Sunday and continues until the beginning of Advent.