Agnipurāṇa (Agnipurana) says about itself — āgneye hi purāṇe’smin sarvā vidyā pradarśitāḥ

This means that every branch of knowledge that people need to possess is contained in it. There is not a single aspect concerning the world and life that has been left out of the Agnipurāṇa. This Purāṇa has a total of 383 chapters. According to Bhāgavatapurāṇa (Bhagavatapurana), Agnipurāṇa, one of the eighteen Mahāpurāṇa (great Purāṇas), has 15,400 verses. According to Nāradapurāṇa (Naradapurana), the number of verses is 15,000, but Matysapurāṇa (Matsyapurana) sets this number at 16,000. However, the text known today as Agnipurāṇa is markedly different and scholars do not consider it to be the original Agnipurāṇa due to several reasons. First, according to Matsyapurāṇa and Skandapurāṇa (Skandapurana), Agnipurāṇa is that Purāṇa which was recounts the details of the era lorded by Īśāna [Ishan; an incarnation of Sīva (Shiva)] and where Agni is the narrator and Vaśisṭha (Vashishtha) the audience. But though the narrator and audience are same in the given text of Agnipurāṇa of today, it does not record the narrative of the Īśāna era (Īśānakalpa). Secondly, the verses cited from Agnipurāṇa by Smṛti (Smriti) scholars are not to be found in the text of Agnipurāṇa that is commonly known. As a result, scholars are of the belief that the main Agnipurāṇa had a different style and content and perhaps used to go by the name of Āgneyapurāṇa or Bahṇipurāṇa in the past.

Agnipurāṇa discusses the essential activities, beliefs and customs of life that bring happiness to it. It includes a summary of Rāmāyaṇa (Ramayana) and Mahābhārata (Mahabharata). Apart from these are included descriptions of the methods of building temples, ways of installing a deity, ways of worship, astrology, the principles of religion and politics, various penances, āyurveda (ayurveda) or medical treatises, treatises on horses and elephants and a plethora of such topics. Most importantly, the thing that sets Agnipurāṇa apart from other Purāṇas is its discussion on Indian poetics and aesthetics. It speaks about various aspects and styles of dramaturgy, choreography, the stage, appraisal of the actors, figures of speech, rhetoric and prosody, Vedic and popular rhythms and above all grammar – and this has made this Purāṇa a veritable treasure house of ancient Indian life to the rest of the world. In its discussion of the philosophy of religion, it has dealt with topics such as the Aṣṭāṅga Yoga (Ashtanga yoga), Vedānta and the essence of Bhagavadgīta (Bhagavadgita).

Ancient dissertations do not contain continuous descriptions of the contents of the ancient Āgneyapurāṇa or Bahṇipurāṇa. However, from the citations in those articles and treatises indicate that thevariety of topics on which this ancient Purāṇa discoursed included rituals of bringing peace from miscellaneous troubles, various forms of charity, the bestowal of gardens and  ponds, the auspiciousness of time of birth and death, cremation, the means of freedom from impurity, Yama (the god of death), customs, fasting, the ritual of Viṣṇu’s bathing journey, types of Śāligrāma (Shalgram; a fossilized shell used as an iconic symbol of Viṣṇu) and points of recognizing the ideal Śāligrāma, and bathing in the holy river Gaṅgā and so on. However, many Smṛti and other experts have cited from the currently popular text of Agnipurāṇa to support their views. Many forms of tāntrika (tantric) rituals mentioned in Agnipurāṇa are still prevalent in modern day Bengal, a fact which has led to the conjecture that Agnipurāṇa was composed in Bengal. Researchers consider this Purāṇa to be composed in the ninth century A.D.