[8] In the classical cosmology of Hinduism, fire (Agni) is one of the five inert impermanent elements (Pañcabhūtá) along with sky (Ākāśa), water (Apas), air (Vāyu) and earth (Pṛthvī), the five combining to form the empirically perceived material existence (Prakṛti).

[5][12][13] He is conceptualized in ancient Hindu texts to exist at three levels, on earth as fire, in the atmosphere as lightning, and in the sky as the sun.

[6] The relative importance of Agni declined in the post-Vedic era,[14] as he was internalised[15] and his identity evolved to metaphorically represent all transformative energy and knowledge in the Upanishads and later Hindu literature.

[16][17][18] Agni remains an integral part of Hindu traditions, such as being the central witness of the rite-of-passage ritual in traditional Hindu weddings called Saptapadi (seven steps and mutual vows), in the Upanayana ceremony of rite of passage, as well being part of the diyā (lamp) in festivals such as Deepavali and Arti in Puja.

[24] Traditional Sanskrit अग्नि (Agni) continues one of two core terms for fire reconstructed to Proto-Indo-European, *h₁n̥gʷnis, other reflexes of which include Albanian: *Enj-i ([ɛɲi]), the reconstructed name of the fire god in the Albanian pagan mythology, which continues to be used in the Albanian language to refer to Thursday (e enjte),[25][26][27] Latin ignis (the root of English ignite), Lithuanian ugnis, Kurdish agir, Old Slavonian огнь (ognĭ)[28] and its descendants: Russian огонь (ogon´), Serbian oganj, Polish ogień, etc., all meaning "fire".

[29] The ancient Indian grammarians variously derived it: In the early Vedic literature, Agni primarily connotes the fire as a god, one reflecting the primordial powers to consume, transform and convey.

[34][35] Yet the term is also used with the meaning of a Mahabhuta (constitutive substance), one of five that the earliest Vedic thinkers believed to constitute material existence, and that later Vedic thinkers such as Kanada and Kapila expanded widely, namely Dyaus (aether), Vayu (air), Varuna (water), Bhumi (earth) and Agni (fire).

With care, he sparks and smokes, then flames and grows stronger than his foster-parents, finally so strong that he burns to ashes what created him his residence by Prajapati.

[56] Agni is in hymn 10.124 of the Rigveda, a Rishi (sage-poet-composer) and along with Indra and Sūrya makes up the Hindu trinity of gods who create, preserve, destroy.

[50] These theme of equivalence is repeatedly presented in the Vedas, such as with the following words in the Maṇḍala 1 of the Rigveda: They call it Indra, Mitra, Varuna, Agni, and he is heavenly-winged Garuda.

The Kena Upanishad closes these sections by stating that "Agni, Vayu, Indra" are revered first because they were the first among the deities to realize Brahman from Parvati.

[73][74] The allegorical legend, states Paul Deussen, aims to teach that all the Hindu deities and natural things have their basis in the timeless, universal monistic principle called Brahman.

[79] The syncretic and monistic Shaivism and Shaktism text, namely Rudrahridaya Upanishad states that Shiva is same as Agni, and Parvati is same as Svaha.

[80][81] Mundaka Upanishad (2.4) mentioned the seven tongues of Agni as kālī, karālī, manojavā, sulohita, sudhāmravarṇā, sphuliṅginī, visvarucī.

He is shown with one to three heads, two to four arms, is typically red-complexioned or smoky-grey complexioned standing next to or riding a ram, with a characteristic dramatic halo of flames leaping upwards from his crown.

[107][108] He is shown as a strong looking man, sometimes bearded, with a large belly because he eats everything offered into his flames, with golden brown hair, eyes and mustache to match the color of fire.

[111][112] The number seven symbolizes his reach in all seven mythical continents in ancient Hindu cosmology where Agni lives and also the seven colours of a rainbow in his form as the sun.

[113] The earliest surviving artwork of Agni have been found at archaeological sites near Mathura (Uttar Pradesh), and these date from 1st-century BCE.

[114]: 215, 366–367, xix, with caption for Figure 86  In the collection at Bharata Kalā Bhavana, there is a red sandstone sculpture from around the start of the common era but no later than 1st-century CE, identifiable as Agni shown in the garb of a Brahmana, very much like sage Kashyapa.

In Gupta sculptures, Agni is found with a halo of flames round the body, the sacred thread across his chest, a beard, pot-bellied and holding in his right hand a amrtaghata (nectar-pot).

However, in rare temples where Agni is envisioned as a presiding astrological divinity, according to texts such as the Samarangana Sutradhara, he is assigned the northeast corner.

[118] In the "Khāṇḍava-daha Parva" (Mahābhārata CCXXV), Agni in disguise approaches Krishna and Arjuna seeking sufficient food for gratification of his hunger; and on being asked about the kind of food which would gratify, Agni expressed the desire to consume the forest of Khāṇḍava protected by Indra for the sake of Takṣaka, the chief of the Nāgas.

Thomas Coburn states that the term Svadhā refers to "one's own particular nature or inclination", and the secondary sense of "a customary pleasure or enjoyment, a refreshment that nourishes".

[126] Agni is identified with same characteristics, equivalent personality and stated to be identical as many major and minor gods and goddesses in different layers of the Vedic literature, including Vāyu, Soma, Rudra, Varuṇa, Mitra, Savitr, Prajapati, Indra, Vac, Sarama, Gayatri.

[137] The Aggi-Vacchagotta Sutta, presents a philosophical exchange between Buddha and a wandering ascetic named Śreṇika Vatsagotra (Sanskrit; Pali: Senika Vacchagotta).

[143] The Tibetan iconography for Agni strongly resembles that found in the Hindu tradition, with elements such as red-colored skin, a goat vehicle, conical hair and crown, a beard, and wielding a pot of water or fire in one hand, and rosary beads in the other.

Such art will often include Buddhist themes such as the dharma wheel, white conch, golden fish, elephant, the endless knot.

Medieval era Thai literature describes him as a deity with seven tongues, a purple crown of smoke, and fiery complexion.

He is one of the eight dikpalas, or directional guardian deities in Jain temples, along with these seven: Indra, Yama, Nirrti, Varuna, Vayu, Kubera and Ishana.

[23] Agni or Tejas are terms used to describe substances and concepts that create beings, and in which transmigrating soul gets bound according to Jainism theology.