What is Advent?
Answer: Advent (from the Latin adventus, arrival), preparation of the celebration of the birth of Christ, points to the coming of the saviour in the flesh, i.e. as a humble human being (Incarnation) and also points to his coming in glory at the end of time (parousia). Advent begins on the 4th Sunday before Christmas. The reformed Churches also celebrate Advent. The Eastern Churches, however, do not know Advent as a liturgical period. On the last Sunday before Christmas the Byzantine Church remembers Christ’s ancestors (the Gospel according to Matthew 1:1-15). The Syrians call the four (East Syrians ) / five (West Syrians) weeks before Christmas weeks of proclamation.
Nr 524 of the “Catechism of the Catholic Church” talks of the advent liturgy and therefore of the spiritual purpose of the period of advent:
524 When the Church celebrates the liturgy of Advent each year, she makes present this ancient expectancy of the Messiah, for by sharing in the long preparation for the Saviour's first coming, the faithful renew their ardent desire for his second coming (c.f. Revelation 22:17). By celebrating the precursor's birth and martyrdom, the Church unites herself to his desire: "He must increase, but I must decrease." (John 2:30).