Advent Sunday is a term that refers to the first Sunday in Advent, which marks the beginning of the Christian season leading up to Christmas. This day is commonly celebrated as a time of preparation for the coming of Christ. While Advent Sunday is the most popular term used for this day, there are also other terms that can be used as synonyms. Some other names for the first Sunday of Advent include the "Sunday of the Holy Nativity" or "Expectation Sunday". In addition, some churches simply refer to this day as "Advent I". Regardless of the term used, Advent Sunday is an important time for Christians around the world to reflect on the meaning of Christmas and what it means in their own lives.