Catechism of the Catholic Church
“The liturgy of the Eucharist unfolds according to a fundamental structure which has been preserved throughout the centuries down to our own day. It displays two great parts that form a fundamental unity: – the gathering, the liturgy of the Word, with readings, homily and general intercessions; – the liturgy of the Eucharist, with the presentation of the bread and wine, the consecratory thanksgiving, and communion. “
Source: Catechism of the Catholic Church #1346