Catechism of the Catholic Church §1574 — excerpt
As in all the sacraments additional rites surround the celebration. Varying greatly among the different liturgical traditions, these rites have in common the expression of the multiple aspects of sacramental grace.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.