Advaita vedānta

Advaita Vedanta is considered as the most influential and most dominant sub-school of the Vedānta (literally, end or the goal of the Vedas, Sanskrit) school of Hindu philosophy. Other major sub-schools of Vedānta are Dvaita and Viśishṭādvaita; while the minor ones include Suddhadvaita, Dvaitadvaita and Achintya Bhedabheda. Advaita (literally, non-duality) is a system of thought where "Advaita" refers to the identity of the Self (Atman) and the Whole (Brahman).
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. The first person to explicitly consolidate the principles of Advaita Vedanta was Adi Shankara, while the first historical proponent was Gaudapada, the guru of Shankara's guru Govinda Bhagavatpada. Adi Shankara's system (i.e., Advaita) is unmatched (with other schools) for its metaphysical depth and logical power.