Reformed churches are a branch of Protestant Christianity that emerged during the Reformation in the 16th century. They emphasize the sovereignty of God, the authority of Scripture, and salvation by grace through faith. Key figures in the Reformed tradition include John Calvin and Huldrych Zwingli, who shaped its theological foundations. These churches often adhere to confessions and catechisms, such as the Westminster Confession of Faith and the Heidelberg Catechism. Worship in Reformed churches typically focuses on preaching, prayer, and the sacraments of baptism and communion, reflecting their commitment to biblical teachings and community life.