Catholicism refers to the traditions, beliefs, and behaviors of the Catholic Church, which is the largest Christian church in the world with 1.3 billion baptized Catholics worldwide as of 2019. The Catholic Church is among the worlds oldest and largest international institutions, and has played a prominent role in the history and development of Western civilization. The church consists of 24 sui iuris churches, including the Latin Church and 23 Eastern Catholic Churches, which comprise almost 3,500 dioceses and eparchies located around the world.

The core beliefs of Catholicism are found in the Nicene Creed, which includes belief in one God, the Father almighty, maker of heaven and earth, of all things visible and invisible, and in one, holy, catholic and apostolic Church. The Catholic Church teaches that it is the one, holy, catholic and apostolic church founded by Jesus Christ in his Great Commission, that its bishops are the successors of Christs apostles, and that the pope is the successor to Saint Peter, upon whom primacy was conferred by Jesus Christ.

Catholicism is not just a religion, but also a way of life and a community. It is a Christian tradition characterized by specific liturgical, ethical, and spiritual orientations and behaviors, and is a people, or cluster of peoples, with a particular history. Catholicism is not a reality that stands by itself, but rather refers to a community of persons who believe in God and shape their lives according to that belief.

Catholicism recognizes seven sacraments, which are important means of grace for the Christian life. These include Baptism, the Eucharist, confirmation, reconciliation (penance), anointing of the sick, marriage, and ordination.

In summary, Catholicism is a Christian tradition and the largest Christian church in the world. Its core beliefs are found in the Nicene Creed, and it recognizes seven sacraments. It is not just a religion, but also a way of life and a community.