Two quotes on Advent from the always-reliable Wikipedia:
Advent (from the Latin word advenio, meaning “to come”, “the coming of Christ our saviour”) is a holy season of the Christian church, the period of expectant waiting and preparation for the celebration of the Nativity of Christ, also known outside the Church as the season of Christmas.
From the 4th century, the season was kept as a period of fasting as strict as that of Lent (commencing in some localities on 11 November; this being the feast day of St. Martin of Tours, the fast became known as “St. Martin’s Fast,” “St. Martin’s Lent” or “the forty days of St. Martin”).
Two resolutions: One, never again will I refer to this season as “the Christmas season.” Two, although I will probably not leap directly to keeping a 40-day fast, I will now proceed to think of the season of Advent as a time of penitential (yet still joyful) anticipation of Christmas Day.