The Rinzai school of Zen Buddhism is one of the major branches of Zen, emphasizing direct experience and sudden enlightenment. Founded in the 12th century by Eisai, it incorporates the use of koans, which are paradoxical questions or statements designed to provoke deep thought and insight. Rinzai practitioners often engage in intense meditation sessions known as zazen, focusing on the koans to break through conventional thinking. This school values rigorous training and discipline, aiming to achieve a state of awakening known as satori, which is seen as a key goal in Zen practice.