The Protestant Reformation was a religious movement in the 16th century that aimed to reform the practices and beliefs of the Roman Catholic Church. It began when figures like Martin Luther challenged the Church's authority and criticized practices such as the sale of indulgences. Luther's 95 Theses, posted in 1517, sparked widespread debate and led to the formation of new Christian denominations. As a result of the Reformation, various groups emerged, including the Lutherans and Calvinists. The movement not only transformed religious practices but also had significant social and political impacts across Europe, contributing to the rise of individualism and the questioning of traditional authority.