Advaita Vedanta is the oldest extant sub-school of Vedanta, an ancient Hindu tradition of scriptural exegesis and religious practice, and the best-known school of advaita, the nonduality of Atman and Brahman or the Absolute. It gives ""a unifying interpretation of the whole body of Upanishads"", providing scriptural authority for the postulation of the nonduality of Atman and Brahman.Advaita (not-two in Sanskrit) refers to the recognition that the true Self, Atman, is the same as the highest Reality, Brahman. Followers seek liberation/release by acquiring vidyā (knowledge) of the identity of Atman and Brahman. Attaining this liberation takes a long preparation and training under the guidance of a guru. Advaita thought can also be found in non-mainstream Indian religious traditions, such as the tantric Nath tradition.The principal, though not the first, exponent of the Advaita Vedanta-interpretation was Shankara Bhagavadpada in the 8th century, who systematised the works of preceding philosophers. Its teachings have influenced various sects of Hinduism.The key source texts for all schools of Vedānta are the Prasthanatrayi, the canonical texts consisting of the Upanishads, the Bhagavad Gita and the Brahma Sutras, of which they give a philosophical interpretation and elucidation.Advaita Vedanta developed in a multi-faceted religious and philosophical landscape. The tradition developed in interaction with the other traditions of India: Jainism, Buddhism, Vaishnavism and Shaivism, as well as the other schools of Vedanta.In modern times, due to western Orientalism and Perennialism, and its influence on Indian Neo-Vedanta and Hindu nationalism, Advaita Vedanta has acquired a broad acceptance in Indian culture and beyond as the paradigmatic example of Hindu spirituality, despite the wide popularity of the Shaivite Vishishtadvaita and Dvaitadvaita bhakti traditions, and incorporating teachers such as Ramana Maharshi and Nisargadatta Maharaj.