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The public prayers of the Church, other than those in the great sacrifice of the Mass, are contained in the Breviary.

The whole Office for each day consists of:
Matins, or Morning Song;
Lauds, or the Divine praises;
Prime, Tierce, Sext, and None, or the prayers for the first, third, sixth, and ninth hours, the old Roman division of the day
Vespers, or Even Song;
and Compline, or the Conclusion

. This office was originally chanted daily by the faithful, and is still chanted by some religious orders, the preservers of primitive tradition and fervor. It is daily recited by the clergy; and on Sundays and holidays the Vespers are publicly chanted as part of the solemn worship of the day, to enable the faithful to join in so holy and venerable a form of prayers. The chant is inseparable from worship; and the Church, selecting the solemn Gregorian tones, condemns the frivolous worldly music, which it so little resembles.

All the parts of the office consist of psalms and canticles from the Scripture, with lessons also from Scripture, or the Holy Fathers, and appropriate to the day.

The psalms in the Vespers for Sundays are the 109th, and the following, including the 113th, although, very frequently, the 116th is substituted for the last of these. This series of psalms is most suitable to the ordinary wants of the Church on her weekly festivals. The first is a kind of commemorates of all the great mysteries of our redemption; the second alludes to the praise of God "in the congregation;" the third commemorates the graces and privileges of the just; the fourth is a psalm of praise, as is also that substituted occasionally for the fifth; the fifth celebrates the deliverance of the Israelites from Egyptian bondage. All are prophecies of our Lord and of His Immaculate mother, as well as of the Church. In them we chant Christ, our Lord, as priest forever, offering sacrifice, like Mechizedec, in the form of bread and wine; as Lord of Lords, and King of kings; as true to His promises of ever abiding by His Church, investing her with miraculous powers; and ever spreading the mystic banquet: in them we chant Him as our Redeemer and our God, whom we adore; in them we chant that Immaculate Virgin - the "joyful mother of many children," - and with her raise our hearts and voices to glorify God.

It is not, then, an unmeaning service; but one most appropriate and consoling. Hence, though it is not of obligation to attend Vespers, as it is to hear Mass, all the saints and spiritual writers of the Church urge the faithful to be present at it with piety and devotion. For there is always more benefit and comfort to be derived from the public offices of the Church, than from private devotions, God having ordained that communion of prayers should always have the preference.

Source: St. John's manual : a guide to the public worship and services of the Catholic Church, and a collection of devotions for the private use of the faithful.