The term hierarchy (literally, "holy government") has a variety of related usages in the Catholic Church. There is a hierarchy of truths, which refers to the levels of solemnity of the official teaching of the faith. There is a hierarchical nature of the church, which is a structural feature considered to be of divine institution.

Most commonly, it refers to the ordering of ministry in the church into the threefold order of episcopate, presbyterate, and diaconate, which is considered to be divinely instituted and essential to the Church itself. In some cases, it refers only to the magisterium, the official teaching body of the church, the bishops, excluding deacons and presbyters (priests).

There is, in addition, an order of precedence of the various offices and ministries, which indicates the precedence or 'rank' of various ministers and offices in the Church for use during liturgies or other ceremonies where such protocol is helpful.

The Catholic Church comprised, as of 31 December 2011, 2,834 dioceses, each overseen by a bishop. Dioceses are divided into individual communities called parishes, each staffed by one or more priests. Priests may be assisted by deacons. All clergy, including deacons, priests, and bishops, may preach, teach, baptize, witness marriages and conduct funeral liturgies. Only priests and bishops are allowed to administer the sacraments of the Eucharist, Reconciliation (Penance), Confirmation (priests may administer this sacraments with prior ecclesiastic approval), and Anointing of the Sick. Only bishops can administer the sacrament of Holy Orders, which ordains someone into the clergy.

The Catholic Church, also known as the Roman Catholic Church, is the world's largest Christian church, with more than one billion members. Led by the Pope, it defines its mission as spreading the Gospel of Jesus Christ, administering the sacraments and exercising charity.

The Catholic Church is among the oldest institutions in the world and has played a prominent role in the history of Western civilisation. It teaches that it is the one true Church founded by Jesus Christ, that its bishops are the successors of Christ's apostles and that the Pope is the sole successor to Saint Peter.

Catholic doctrine maintains that the Church is infallible when it dogmatically teaches a doctrine of faith or morals. Catholic worship is centred on the Eucharist in which the Church teaches that bread and wine become the body and blood of Christ.

The Church holds the Blessed Virgin Mary in special regard. Catholic beliefs concerning Mary include her Immaculate Conception without original sin, her Motherhood of God and her bodily Assumption into Heaven at the end of her earthly life.