As explained in greater detail in the Catechism of the Catholic Church and its shorter Compendium, the liturgy is something that "the whole Christ", Head and Body, celebrates — Christ, the one High Priest, together with his Body, the Church in heaven and on earth. Involved in the heavenly liturgy are the angels and the saints of the Old Covenant and the New, in particular Mary, the Mother of God, the Apostles, the Martyrs and "a great multitude, which no man could number, out of every nation and of all tribes and peoples and tongues" (Revelation 7:9). The Church on earth, "a royal priesthood" (1 Peter 2:9), celebrates the liturgy in union with these: the baptized offering themselves as a spiritual sacrifice, the ordained ministers celebrating at the service of all the members of the Church in accordance with the order received, and bishops and priests acting in the person of Christ.
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, confirmation to Christ and 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.
There are seven Sacraments: