Marriage (the Sacrament of) is a lasting commitment of a man and a woman to a lifelong partnership, established for the good of each other and the procreation of their children.
The Sacrament of Marriage is a covenant, which is more than a contract. Covenant always expresses a relationship between persons. The marriage covenant refers to the relationship between the husband and wife, a permanent union of persons capable of knowing and loving each other and God. The celebration of marriage is also a liturgical act, appropriately held in a public liturgy at church. Catholics are urged to celebrate their marriage within the Eucharistic Liturgy.
Visit the Catechism of the Catholic Church for more information on the Sacrament of Matrimony.