Catechism of the Catholic Church §2637 — excerpt
Thanksgiving characterizes the prayer of the Church which, in celebrating the Eucharist, reveals and becomes more fully what she is. Indeed, in the work of salvation, Christ sets creation free from sin and death to consecrate it anew and make it return to the Father, for his glory.
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.