Śruti

"Shruti" (Sanskrit, IAST: śruti) means "that which is heard" and refers to the body of most authoritative, ancient religious texts comprising the central canon of Hinduism. It includes the four Vedas including its four types of embedded texts - the Samhitas, the Brahmanas, the Aranyakas and the early Upanishads.

Shrutis have been considered revealed knowledge, variously described as of divine origin, or nonhuman primordial origins. In Hindu tradition, they have been referred to as apauruṣeya (authorless). All six orthodox schools of Hinduism accept the authority of śruti, but many scholars in these schools denied that the shrutis are divine.Nāstika (heterodox) philosophies such as the Cārvākas did not accept the authority of the shrutis and considered them to be flawed human works.

Shruti differs from other sources of Hindu philosophy, particularly smṛti “which is remembered” or textual material. These works span much of the history of Hinduism, beginning with the earliest known texts and ending in the early historical period with the later Upanishads. Of the śrutis, the Upanishads alone are widely known, and the central ideas of the Upanishadic śrutis are at the spiritual core of Hindus.