In Hinduism, Brahman (ब्रह्मन्) connotes the highest universal principle, the ultimate reality in the universe. In major schools of Hindu philosophy, it is the immaterial, efficient, formal and final cause of all that exists. It is the pervasive, infinite, eternal truth, consciousness and bliss which does not change, yet is the cause of all changes. Brahman as a metaphysical concept refers to the single binding unity behind diversity in all that exists in the universe.
Brahman is a Vedic Sanskrit word, and it is conceptualized in Hinduism, states Paul Deussen, as the "creative principle which lies realized in the whole world". Brahman is a key concept found in the Vedas, and it is extensively discussed in the early Upanishads. The Vedas conceptualize Brahman as the Cosmic Principle. In the Upanishads, it has been variously described as Sat-cit-ānanda (truth-consciousness-bliss) and as the unchanging, permanent, highest reality.
Brahman is discussed in Hindu texts with the concept of Atman (आत्मन्), (Self), personal, impersonal or Para Brahman, or in various combinations of these qualities depending on the philosophical school. In dualistic schools of Hinduism such as the theistic Dvaita Vedanta, Brahman is different from Atman (Self) in each being. In non-dual schools such as the Advaita Vedanta, the substance of Brahman is identical to the substance of Atman, is everywhere and inside each living being, and there is connected spiritual oneness in all existence.
Sanskrit (ब्रह्मन्) Brahman (an n-stem, nominative , from a root - "to swell, expand, grow, enlarge") is a neuter noun to be distinguished from the masculine —denoting a person associated with Brahman, and from Brahmā, the creator God in the Hindu Trinity, the Trimurti. Brahman is thus a gender-neutral concept that implies greater impersonality than masculine or feminine conceptions of the deity. Brahman is referred to as the supreme self. Puligandla states it as "the unchanging reality amidst and beyond the world", while Sinar states Brahman is a concept that "cannot be exactly defined".