Catechism of the Catholic Church §1057 — excerpt
Hell's principal punishment consists of eternal separation from God in whom alone man can have the life and happiness for which he was created and for which he longs.
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.