Adi Shankara (Malayalam: ആദി ശങ്കരന്, Devanāgarī: आदि शङ्कर, Ādi Śaṅkara, IPA: Dates Section], also known as Śaṅkara Bhagavatpādācārya ("the teacher at the feet of God"), and Ādi Śaṅkarācārya ("the first Shankara in his lineage") was the first philosopher to consolidate the doctrine of Advaita Vedanta, a sub-school of Vedanta. His teachings are based on the unity of the soul and Brahman, in which Brahman is viewed as without attributes. In the Smārta tradition, Adi Shankara is regarded as an incarnation of Shiva.
Adi Shankara toured India with the purpose of propagating his teachings through discourses and debates with other philosophers. He founded four mathas ("monasteries") which played a key role in the historical development, revival and spread of post-Buddhist Hinduism and Advaita Vedanta. Adi Shankara was the founder of the Dashanami monastic order and the Shanmata tradition of worship.
His works in Sanskrit, all of which are extant today, concern themselves with establishing the doctrine of Advaita (Sanskrit, "Non-dualism"). Adi Shankara quotes extensively from the Upanishads and other Hindu scriptures in forming his teachings. He also includes arguments against opposing schools of thought like Samkhya and Buddhism in his works.