The Catholic Church provides three different forms of celebrating the Rite of Marriage. When two Catholics are marrying, the celebration will normally take place within a Mass. The second form, which does not include a Mass, is used when a Catholic marries another baptized Christian. A third form, also outside Mass, is usually celebrated when a Catholic marries someone who is not baptized. The second and third forms are structured around the celebration of the Liturgy of the Word.
Watch a video by the United States Conference of Catholic Bishops to learn more: