The Holy Spirit prepares the faithful for the sacraments by the Word of God and the faith welcomes that word in well-disposed hearts. Thus the sacraments strengthen faith and express it. (Cathecism of the Catholic Church (CCC) , No. 1133) Or, in an older version of the definition, sacraments are outward signs, insituted by Christ, which confer grace.
Sacraments of Initiation: Baptism, Confirmation and Eucharist
Baptism, confirmation and Eucharist are the sacraments of initiation, whereby a person is fully incorporated into the church and the Body of Christ. For adults, preparation for these sacraments is accomplished through the Rite of Christian Initiation of Adults (RCIA). The RCIA process, for those who have discerned their entrance into the Catholic Church, culminates in the celebration of the sacraments of initiation at the Easter Vigil.
For families with children, the sacraments of initiation are usually celebrated according to a prescribed schedule as part of the Parish Faith Formation program.
Sacraments of Vocation: Marriage and Holy Orders
God is the author of marriage. That intimate community of life and love which constitutes the married state has been established by the Creator and endowed with its own proper laws. (CCC, No. 1603) The matrimonial covenant, by which a man and a woman establish between themselves a partnership of the whole of life is ordered toward the good of the spouses and the procreation and education of children and has been raised by Christ the Lord to the dignity of a sacrament. (CCC, No. 1601)
Though the whole church is a priestly people with all the baptized faithful sharing in the priesthood of Christ [CCC, No. 1591], the sacrament of holy orders ensures that the mission entrusted by Christ to his apostles continues to be exercised in the church through ordained bishops, priests and deacons. (CCC, No. 1536).
Sacraments of Healing: Penance and Anointing
Christ instituted the sacrament of penance for all the members of the church who have sinned: above all for those who, since baptism, have fallen into sin. It is to them that the sacrament of penance offers a new possibility to convert and to recover the grace of justification. (CCC, No. 1446)
Anointing of the sick is not intended only for those who are at the point of death. As soon as anyone begins to be in danger of death from sickness or old age, the time to receive the sacrament has arrived. (CCC, No. 1514) Through the sacrament, the church commends those who are ill to the suffering and glorified Lord, that he may raise them up and save them. (CCC, No. 1499)