Church Seasons and Special Sundays
The Christian Church Year begins four weeks before Christmas with the Season of Advent focusing on the theme of Anticipation.
This is followed by the 12 days of Christmas beginning on Christmas Day, celebrating the birth of Jesus of Nazareth.
Epiphany is always January 6 celebrating the visit of the Magi (the Wise Men) followed by a Sunday celebrating Jesus' baptism and other Sundays wherein the focus is on Jesus' ministry.
Lent begins on Ash Wednesday which is 40 days before Easter (not counting Sundays, which are always celebration of the Resurrection). The days of Lent focus on self-examination and the suffering and sacrifice of Christ. It concludes with Holy Week which begins with Palm/Passion Sunday and includes Maundy Thursday and Good Friday.
Easter is held on the first Sunday following the first full moon after the Spring Equinox, and it celebrates the Resurrection of Christ. It is a season of 49 days (a week of seven weeks)
Pentecost (the Birthday of the Church) is on the 50th day after Easter. The Sundays following in the Church year are counted as "Sundays after Pentecost" and focus on the life and teachings of the Church.