In the Catholic Church, Advent is a period of preparation, extending over four Sundays, before Christmas. "Advent is a period beginning with the Sunday nearest to the feast of St. Andrew the Apostle (30 November) and embracing four Sundays." That means that the First Sunday of Advent can fall as early as November 27 or as late as December 3. Advent 2014 begins on the First Sunday in Advent, November 30th.
The word Advent comes from the Latin advenio, "to come to," and thus refers to the coming of Christ. This refers, first of all, to our celebration of Christ's birth at Christmas; but second, to the coming of Christ in our lives through grace and the Sacrament of Holy Communion; and finally, to His Second Coming at the end of time