The Catholic Church is fundamentally liturgical and sacramental in its public life of worship.
The Catholic liturgy uses signs and symbols whose significance, based on nature or culture, has been made more precise through Old Testament events and has been fully revealed in the person and life of Christ. Some of these signs and symbols come from the world of creation (light, water, fire, bread, wine, oil), others from life in society (washing, anointing, breaking bread), others from Old Testament sacred history (the Passover rite, sacrifices, laying on of hands, consecrating persons and objects).
These signs are closely linked with words. Though in a sense the signs speak for themselves, they need to be accompanied and vivified by the spoken word. Taken together, word and action indicate what the rite signifies and effects.
Sacraments in the Catholic Church are efficacious signs, perceptible to the senses, of grace. According to the Church's theology, they have been instituted by Christ and entrusted to the Church, and through them divine life is bestowed on us. They are means by which Christ gives the particular grace indicated by the sign aspect of the sacrament in question, helping the individual to advance in holiness, and contributing to the Church' s growth in charity and in giving witness. Not every individual receives every sacrament, but the Catholic Church sees the sacraments as necessary means of salvation for the faithful, conferring each sacrament's particular grace, whether forgiveness of sins, adoption as children of God, conformation to Christ, or membership of the Church. The effect of the sacraments comes ex opere operato (by the very fact of being administered). Regardless of the personal holiness of the minister administering the sacraments, Christ provides the graces of which they are signs. However, a recipient's own lack of proper disposition to receive the grace conveyed can block their effectiveness in that person. The sacraments presuppose faith and, in addition, their words and ritual elements nourish, strengthen and give expression to faith.[Compendium of the Catechism of the Catholic Church'', 224]
There are seven Sacraments:
Also associated with the liturgy are sacred images, which proclaim the same message as do the words of Sacred Scripture sung to the sacred melodies of the chant, and which help to awaken and nourish faith.
In addition to the sacraments, instituted by Christ, there are many sacramentals, sacred signs (rituals or objects) that derive their power from the prayer of the Church. They involve prayer accompanied by the sign of the cross or other signs. Important examples are blessings (by which praise is given to God and his gifts are prayed for), consecrations of persons, and dedications of objects to the worship of God.
Popular devotions are not strictly part of the liturgy, but if they are judged to be authentic, the Church encourages them. They include veneration of relics of saints, visits to sacred shrines, pilgrimages, processions (including Eucharistic processions), the Stations of the Cross (also known as the Way of the Cross), Holy Hours, Eucharistic Adoration, Benediction of the Blessed Sacrament, and the Rosary.
In its devotion the Church makes a distinction (Catechism of the Catholic Church, s2132) between respectful veneration on one hand and adoration or worship on the other. Adoration is due to God alone - this includes the Eucharist, since Christ is truly present. Veneration of an image or relic of a saint is defined as respect paid to what is represented in the image, not the image itself.
The Liturgy of the Hours consecrates to God the whole course of day and night. Lauds and Vespers (morning and evening prayer) are the principal hours. To these are added one or three intermediate prayer periods (traditionally called Terce, Sext and None), another prayer period to end the day (Compline), and a special prayer period called the Office of Readings (formerly known as Matins) at no fixed time, devoted chiefly to readings from the Scriptures and ecclesiastical writers. The Second Vatican Council suppressed an additional 'hour' called Prime. The prayers of the Liturgy of the Hours consist principally of the Psalter or Book of Psalms. Like the Mass, the Liturgy of the Hours has inspired great musical compositions. An earlier name for the Liturgy of the Hours and for the books that contained the texts was the Divine Office (a name still used as the title of one English translation), the Book of Hours, and the Breviary. Bishops, priests, deacons and members of religious institutes are obliged to pray at least some parts of the Liturgy of the Hours daily, an obligation that applied also to subdeacons, until the post VCII suppression of the subdiaconate.
The richness of the Mystery of Christ cannot be exhausted by any one liturgical tradition and has from the beginning found varied complementary expressions characteristic of different peoples and cultures. As catholic or universal, the Church believes it can and should hold within its unity the true riches of these peoples and cultures.
There are in the liturgy, specifically in the sacraments, elements that cannot be changed, because they are of divine institution. These the Church must guard carefully. Other elements may be changed, and the Church has the power, and sometimes the duty, to adapt them to the different cultures of peoples and times.