Ans. The Upanishads are a collection of ancient Hindu scriptures that form the basis of philosophical and spiritual teachings in Hinduism. They were composed between 800 and 200 BCE and are considered the culmination of Vedic thought. The Upanishads explore topics such as the nature of reality, the self (Atman), and the ultimate truth (Brahman). They emphasize the importance of self-realization and the pursuit of spiritual knowledge.