Advent, anglicized from the Latin word adventus meaning "coming", is a season observed in many Western Christian churches, a time of expectant waiting and preparation for the celebration of the Nativity of Jesus at Christmas. It is the beginning of the Western liturgical year and commences on Advent Sunday, called Levavi. The Eastern churches' equivalent of Advent is called the Nativity Fast, but it differs both in length and observances and does not begin the church year, which starts instead on September 1.
The progression of the season may be marked with an Advent calendar, a practice introduced by German Lutherans. At least in the Roman Catholic, Anglican, Lutheran, Moravian, Presbyterian and Methodist calendars, Advent starts on the fourth Sunday before December 25, the Sunday from November 27 to December 3 inclusive.
(... from Wikipedia on 2012-04-17 07:20:34)