Presbyterianism is part of the Reformed churches family of denominations of Christian Protestantism based on the teachings of John Calvin which traces its institutional roots to the Scottish Reformation, especially as led by John Knox. There are many separate institutional entities that subscribe to Presbyterianism, in different nations around the world. Besides national distinctions, Presbyterians also have divided from one another for doctrinal reasons, especially in the wake of the Enlightenment.
These denominations derive their name from the Greek word presbyteros, which literally means "elder." Presbyterian church governance is common to the Protestant churches that were most closely modelled after the Reformation in Switzerland. In England, Scotland and Ireland, the Reformed churches that adopted a presbyterian instead of episcopalian government, became known naturally enough, as the Presbyterian Church.
Presbyterians distinguish themselves from other denominations by both doctrine and institutional organization, or as they prefer to call it 'church order'. The origins of the Presbyterian churches were in Calvinism, which is no longer taught by some of the contemporary branches. Many of the branches of Presbyterianism are remnants of previous splits from larger groups. These splits have been caused by disagreement concerning the degree to which those ordained to church office should be required to agree with the Westminster Confession of Faith, which historically serves as the main constitutional document of Presbyterian churches. Those groups that adhere to the document most strictly are typified by baptism of the infant children of members, the exclusive use of Psalms (modified for metrical singing), singing unaccompanied by instruments, a common communion cup, only men are eligible for ordination to any church office, and a fully Calvinist doctrine of salvation. Because of this diversity of belief, more conservative Presbyterians are likely to attend the smaller denominations that have chosen to split from a larger body. While these conservative Presbyterians are not in the majority, their numbers are significant.
Presbyterian church order is based on two congregationally elected bodies, the Elders and the Deacons. Elders are typically in charge of relations with the larger denomination, doctrine, membership in the particular congregation, and relations between the pastor and the congregation. Ministers are called by individual churches and in a three-way agreement. A call is issued for the clergy to serve a particular congregation in conjunction with the Presbytery or higher governing body. The people that formerly handled the financial affairs of the church were the Trustees. The Trustees no longer exist in most Presbyterian churches because their jobs are being handled by the session, made up of Elders. Each congregation elects representatives to a local assembly, often called a presbytery. A presbytery elects representatives to a broader regional synod, and the synods elect representatives to the General Assembly. This congregation / presbytery / synod / general assembly schema is based on the larger Presbyterian churches, like the Church of Scotland; some of the smaller bodies, like the Presbyterian Church in America skip one of the steps between congregation and General Assembly, and usually the step skipped is the Synod.
Presbyterians place great importance upon education and continuous study of the scriptures, theological writings, and understanding and interpretation of church doctrine embodied in several statements of faith and catechisms formally adopted by various branches of the church. References to the adoption of Calvin's theology of predestination and the typical member's predisposition to conduct themselves "decently and in order" have earned them the moniker of the "frozen chosen". However, most Presbyterians generally exhibit their faith in action more than words, including generosity, hospitality, and the constant pursuit of social justice and reform.