The Upanishads (Devanagari: उपनिषद्, IAST: upaniṣad) have been regarded as the crown of the Vedas and form the Hindu scriptures which primarily discuss philosophy, meditation, and the nature of God; they form the core spiritual thought of Vedantic Hinduism. Considered as mystic or spiritual contemplations of the Vedas, their putative end and essence, the Upanishads are known as Vedānta ("the end/culmination of the Vedas").
The Upanishads were composed over several centuries. The oldest, such as the Brhadaranyaka and Chandogya Upanishads, have been dated to around the eighth century BCE.