Final answer:
A koan is a paradoxical question or statement used in Zen Buddhism to provoke enlightenment. In the Rinzai school of Zen Buddhism, koans are used by Zen masters to help students attain a direct experience of truth and reality.
Step-by-step explanation:
A koan is a paradoxical question or statement used in Zen Buddhism to provoke enlightenment and break through the limitations of logical thinking. In the Rinzai school of Zen Buddhism, koans are used as a teaching tool by Zen masters to help students attain a direct experience of truth and reality. Students are given a koan, such as 'What is the sound of one hand clapping?' or 'What did your face look like before your parents were born?', and are asked to contemplate it deeply and provide an intuitive response beyond intellectual analysis. The aim of working with koans is to transcend dualistic thinking and achieve direct insight into the nature of existence and one's own mind.