The holiness movement is a Christian reform movement that emerged in the 19th century, emphasizing the pursuit of personal holiness and a deeper spiritual life through the work of the Holy Spirit. It builds on the teachings of John Wesley, advocating for a second work of grace known as entire sanctification, which is seen as a transformative experience that enables believers to live free from sin. This movement has significantly influenced various denominations and led to the formation of new ones focused on holiness.