in the Upanishads (Upanishad) (Indian sacred writings), the supreme existence or absolute, the font of all things. The etymology of the Sanskrit is uncertain. Though a variety of views are expressed in the Upanishads, they concur in the definition of brahma as eternal, conscious, irreducible, infinite, omnipresent, spiritual source of the universe of finiteness and change. Marked differences in interpretation of brahma characterize the various subschools of Vedānta, the orthodox system of Hindu philosophy based on the writings of the Upanishads.

According to the Advaita (Nondualist) school of Vedānta, brahma is categorically different from anything phenomenal, and human perceptions of differentiation are illusively projected on this reality. The bhedābheda (Dualist–Nondualist) school maintains that brahma is nondifferent from the world, which is its product, but different in that phenomenality imposes certain adventitious conditions (upādhis) on brahma. The Viśiṣṭādvaita (Nonduality of the Qualified) school maintains that a relation between brahma and the world of soul and matter exists that is comparable to the relation between soul and body and that phenomenality is a glorious manifestation of brahma; the school identifies brahma with a personal god, Brahmā, who is both transcendent and immanent. The Dvaita (Dualist) school refuses to accept the identity of brahma and world, maintaining the ontological separateness of the supreme, which it also identifies with a personal god.

In early Hindu mythology, brahma is personified as the creator god Brahmā (Brahma) and placed in a triad of divine functions: Brahmā the creator, Vishnu the preserver, and Śiva the destroyer.