Advent is celebrated by Christians in the weeks leading up to Christmas and marks the beginning of the liturgical year for Christians.

Advent, which comes from the Latin word adventus meaning “coming” or “visit,” begins four Sundays before Christmas and ends Christmas Eve, according to the United Methodist Church.

In 2019, Advent began on Sunday, Dec. 1. During the four weeks prior to Christmas, Christians “prepare for, and anticipate, the coming of Christ” as well as celebrating the birth of Jesus.

The origins of Advent are unknown, but according to some experts it dates back to at least 567, when monks were ordered to fast during the months leading up to Christmas. Some Christians still fast during advent, and some avoid certain foods.

Advent is counted down using Advent calendars, which are often made of paper or cardboard with 24 or 25 windows, which open every day. Sometimes, a picture is displayed beneath, and sometimes there are small treats inside like chocolate. Advent wreaths and candles are used to count down the weeks of Advent, lighting one additional candle each Sunday.

The Christmas season begins at sundown on Dec. 24 through the Epiphany of the Lord on Jan. 6. This period is popularly referred to as “the 12 days of Christmas.”