Advaita, literally “not two”, is the name of the school of Vedānta systematized by Śaṅkara in the eighth century. It holds that Brahman alone is ultimately real, that the world of many things is an appearance superimposed on it through ignorance, and that the individual self is in truth identical with Brahman. Liberation is the direct knowledge of that identity, which removes ignorance as light removes darkness.
Advaita
Nondualism: the Vedānta teaching that the self and ultimate reality, Brahman, are not two.
Also: Advaita Vedānta, nondualism