The Protestant Reformation was a Christian reform movement in Europe. It is thought to have begun in 1517 with Martin Luther's Ninety-Five Theses and may be considered to have ended with the Peace of Westphalia in 1648.
The movement began as an attempt to reform the Catholic Church. Many western Catholics were troubled by what they saw as false doctrines and malpractices within the Church, particularly involving the teaching and sale of indulgences. Another major contention was the practice of buying and selling church positions (simony) and what was seen at the time as considerable corruption within the Church's hierarchy. This corruption was seen by many at the time as systemic, even reaching the position of the Pope.
The reform movement soon split along certain doctrinal lines. Spiritual disagreements between Martin Luther and Zwingli, and later between Luther and John Calvin, led to the emergence of rival Protestant churches. The most important denominations to emerge directly from the Reformation were the Lutherans, and the Reformed/Calvinists/Presbyterians. The process of reform had decidedly different causes and effects in other countries. In England, where it gave rise to Anglicanism, the period became known as the English Reformation. Subsequent Protestant denominations generally trace their roots back to the initial reforming movements. The reformers also accelerated the Catholic or Counter Reformation within the Catholic Church. The Protestant Reformation is also referred to as the German Reformation, Protestant Revolution or Protestant Revolt.