Catholicism is the name given the oldest of the three main branches of Christianity, and to the beliefs of the Catholic Church, usually the Roman Catholic Church, and its adherents. An earlier Webster's Dic lists two ecclesiastical meanings: "the whole orthodox Christian church, or adherence thereto;" and "the doctrines or faith of the Roman Catholic chuch, or adherence thereto." 3 The term comes from the Greekkatholikos (καθολικος), meaning "general" or "universal".
As evident in the notion of "adherence to" the doctrines of the Christian faith, the Catholic Church, in English more than in Romance languages, is something of a disputed term which has several claimants. The claimants have in common an assertion that they represent the ancient undivided Christianfaith, and differ on the practical meaning of "unity" within that faith. Over the centuries, within the Christian faith there arose disputes about the truths of the faith, and vocabulary evolved to reflect divergent viewpoints. "Catholic" and "Orthodox" are examples of such terms, each with a basic meaning, universal and correct respectively, and each with a connotation in speech: hence "Catholic" generally refers to the branch of the Christian faith that accepts the leadership of the Pope, whereas "Orthodox" is used to refer to the several ecclesial communities that gradually split from the Roman Church after the first millenium, in communion with each other, but not accepting the Roman Primacy. After the Protestant Reformation, the newly-formed ecclesial communities in some cases applied the term "Catholic" in an ideal sense, referencing the original Christian faith. 4 For comparisons and contrasts, see Roman Catholic Church, Eastern Orthodoxy, Greek Orthodox Church, , and Protestantism.
The term "Catholic" has been used since the first Christian centuries to describe the one, original church of Christ founded by Christ and the Apostles, and appears in the main Christian creeds (formal definitions of belief), notably the Apostles' Creed and the Nicene Creed. As such, many Christians claim entitlement to the designation "catholic". These fall into two groups: 1.) those like the Roman Catholic, Eastern and Oriental Orthodox, and the Ancient, Old, Liberal, and Anglican Catholic churches that claim Apostolic Succession from the early church; and 2.) those who believe that they are spiritual descendants of the Apostles neither retaining nor desiring organisational descent from the historic church.
Christians of most denominations, including most Protestants, affirm their faith in "one holy catholic and apostolic Church." For Protestants, most of whom consider themselves to be spiritual descendents (category 2, above), this affirmation refers to their belief in the ultimate unity of all churches under one God and one Saviour, rather than in one visibly unified church, i.e. the ideal meaning given above. In this usage catholic is usually written with a minuscule "c". The Nicene Creed stating "I believe in...the holy catholic church..." is thus recited in Protestant worship services. 5.
The Anglican Communion, though one church, is in practice divided into two wings, "High Church Anglicans" also called the Anglo-Catholics and "Low Church Anglicans" also known as the Evangelical wing. Though all elements within the Anglican Communion recite the same creeds, Low Church Anglicans regard the word Catholic in the ideal sense given above, while High Church Anglicans treat it as a name of Christ's church which they consider to embrace themselves together with the Roman Catholic and several Orthodox Churches.
Anglo-Catholicism maintains more similarities to the Latin Rite and related spirituality, including a belief in seven sacraments, Transubstantiation as opposed to Consubstantiation, devotion to the Virgin Mary and saints, the description of their ordained clergy as "priests" - addressed as "Father" - the wearing of vestments in church liturgy, sometimes even the description of their Eucharistic celebrations as "Mass". The development of the Anglo-Catholic wing of Anglicanism occurred largely in the nineteenth century and is strongly associated with the Oxford Movement. Two of its leading lights, John Henry Newman and Henry Edward Manning, both ordained Anglican clergymen, ended up joining the Roman Catholic Church, becoming cardinalss.
The several churches of Eastern Orthodoxy and Oriental Orthodoxy consider themselves to be the "universal" and "true" Catholic Church, and typically regard the Western "Catholics" as heretical and as having left the "true catholic and apostolic church." The Patriarchs of Eastern Orthodoxy are autocephaloushierarchs, which roughly means that each of them is independent of the direct oversight of another bishop (although still subject to their synod of bishops as a whole). They are willing to concede a primacy of honour to the Bishop of Rome, but not obedience to him.
The Eastern Rite Catholics, whose liturgy is similar to that of the Orthodox, allow married men to be ordained as priests, have their own hierarchies with Patriarchs as heads, and recognize the Roman Patriarch as the head of the whole Church. These are among the Churches sui iuris. In 1990 Pope John Paul II promulgated the Code of Canons of the Eastern Churches "in order to safeguard and to promote the specific features of the Eastern heritage." 
Possession of the "threefold ordained ministry" of Bishops, Priests and Deacons.
All ministers are ordained by, and subject to, Bishops, who pass down sacramental authority by the "laying-on of hands", having themselves been ordained in a direct line of succession from the Apostles (see Apostolic Succession).
Their belief that the Church, not any one book, is the vessel and deposit of the fullness of the teachings of Jesus and the Apostles. This teaching is preserved in both written scripture and in written and oral church tradition. Neither is independent of the other.
A belief in the necessity of sacraments (although not necessarily seven in number).
The use of images, candles, vestments and music in worship.
In Catholic teaching, sacraments are gifts of Christ, performed through the office of the Church, that impart sanctifying grace to the receiver. Briefly: Baptism is given to infants and to adult converts who have not previously been validly baptised according to custom; the baptism of most Christian denominations is accepted as valid by the Catholic Church since the effect is believed to come straight from God regardless of the personal faith, but not intention, of the minister. Confession or reconciliation involves admitting sins to a priest and receiving penance (a task to complete in order to show repentance, and so achieve absolution or forgiveness from God). Eucharist (Communion), is considered a partaking in the sacrifice of Christ, marked by sharing the Body and Blood of Christ, which are believed to replace the bread and wine used in the ceremony. The Roman Catholic belief that bread and wine are transformed in all but appearance into the Body and Blood of Jesus Christ is known as transubstantiation. In the sacrament of Confirmation, the gift of the Holy Spirit conferred in baptism is "strengthened and deepened" (see Catechism of the Catholic Church§1303) by the laying on of hands and anointing with oil. In the majority Roman Catholic church, this sacrament is presided over by a bishop, and takes place in early adulthood. It confirms one into full membership of the Church. In the Eastern Catholic Churches the sacrament is called chrismation, and is ordinarily performed immediately after baptism by a priest. Holy Orders is the entering into the priesthood and involves a vow of chastity; the sacrament of Holy Orders is given in three degrees: that of the deacon (since Vatican II a permanent deacon may be married before becoming a deacon), that of the priest, and that of the bishop. Anointing of the Sick used to be known as "extreme unction" or the "last rites"; it involves the anointing of a sick person with a holy oil blessed specifically for that purpose and is no longer limited to the seriously ill or dying. Extreme Unction in its centuries-old form, matter, and intent, however, is still available through hundreds of Catholic priests all over the world.