Catechism of the Catholic Church §1527 — excerpt
The sacrament of Anointing of the Sick has as its purpose the conferral of a special grace on the Christian experiencing the difficulties inherent in the condition of grave illness or old age.
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.