A Christian denomination is an identifiable religious body under a common name, structure, and doctrine within Christianity. In the Orthodox tradition, churches are divided often along ethnic and linguistic lines, into separate churches and traditions. Technically, divisions between one group and another are defined by doctrine and church authority. Issues such as the nature of Jesus, the authority of apostolic succession, eschatology, and papal primacy separate one denomination from another.

The Catholic Church is the largest denomination with over 1.1 billion members, over half of all Christians worldwide, making it the largest denomination for any religion worldwide (although the church does not view itself as a denomination, but as the original pre-denominational church). Protestant denominations comprise roughly 38–39% of Christians worldwide, and together the Catholics, Protestants, Anglicans, and other closely related denominations comprise Western Christianity. The Eastern Orthodox Church, Oriental Orthodox Churches and the Assyrian Church of the East are considered Eastern Christian denominations. Western Christian denominations prevail in Western Europe and its former colonies. Eastern Christian denominations are represented mostly in Eastern Europe, the Middle East and North Africa.

Christians have various doctrines about the Church, the body of faithful that they believe was established by Jesus Christ, and how the divine church corresponds to Christian denominations. Both the Catholics and the Eastern Orthodox consider each of themselves solely to faithfully represent the One Holy Catholic and Apostolic Church to the exclusion of the other. Protestants separated from the Catholic Church because of theologies and practices that they considered to be in violation of their interpretation. Generally, members of the various denominations acknowledge each other as Christians, at least to the extent that they have mutually recognized baptisms and acknowledge historically orthodox views including the Divinity of Jesus and doctrines of sin and salvation, even though doctrinal and ecclesiological obstacles hinder full communion between churches.

Since the reforms surrounding Vatican II, the Catholic Church has referred to Protestant communities as "denominations", while reserving the term "church" for apostolic churches, including the Eastern Orthodox (see subsistit in and branch theory). There are however some non-denominational Christians who do not follow any particular branch.