Upanishads are called Adhyatma Vidya (spiritual knowledge) or Brahma Vidya as they convey the essence of the Veda teachings. They constitute that eternal beacon which has been illuminating the creation right since its inception by its undecayable, eternal and ever-relevant light. Its light contains that element of immortality which has nurtured and nourished the very root of the Sanatana Dharma. It is a unique gift from India to the world for its eternal welfare.
There are believed to be ten Upanishads: Isha, Kena, Katha, Prashna, Mundaka, Mandooka, Mandookya, Taittareeya, Eitareiya, Chandogya and Brihadaaranyaka.