343. How is the sacrament of Matrimony celebrated?Since Matrimony establishes spouses in a public state of life in the Church, its liturgical celebration is public, taking place in the presence of a priest (or of a witness authorized by the Church) and other witnesses.
Further reading: CCC 1621-1624344. What is matrimonial consent?
Matrimonial consent is given when a man and a woman manifest the will to give themselves to each other irrevocably in order to live a covenant of faithful and fruitful love. Since consent constitutes Matrimony, it is indispensable and irreplaceable. For a valid marriage the consent must have as its object true Matrimony, and be a human act which is conscious and free and not determined by duress or coercion.
Further reading: CCC 1625-1632, 1662-1663