The Puranas are ancient Sanskrit books or literary texts that are an integral part of Hindu, Jain and Buddhist religious beliefs. It is believed that the Puranas were composed between 4th century BC and 1000 AD. These texts can almost be viewed as encyclopedias of ancient beliefs as they contain stories about the history of the universe -  from creation to destruction, genealogies of gods, kings, heroes and patriarch sages, and description of Hindu cosmology, philosophy, Puranas are said to have five distinguishing properties, or Pancha Lakshana

Sarga - Creation of the universe.

Pratisarga - Secondary creations, mostly recreations after dissolution.

Vamśa - Genealogy of the gods and sages.

Manvantara - Creation of the human race (race of Manu) and the first human beings (Manavas).

Vamshanucharitam - Histories of the patriarchs of the lunar and solar dynasties.

The word “Purana” means “ancient” in Sanskrit. Sage Vyasa, the narrator of the Mahabharata, is considered to be the compiler of these books. The general line of thought is that the Puranas existed in an oral form for a long time before they were compiled in written texts, around the time when the written composition of Mahabharata was being wrapped up. The Puranas have also been referred to as “the fifth veda” in the Upanishads.

There are eighteen major Puranas, and many minor or subordinate ones.

Agni: About Vastu Shastra and Gemology.

Bhagavata: Stories of Vishnu’s Dashavatar (Vishnu’s ten incarnations). It’s the most popular of all Puranas.

Bhavishya: Prophecies regarding the future

Brahma: About river Godavari and its tributaries. It’s the shortest Purana.

Brahmanda: Account of Brahmanda and the future cosmic ages revealed by Brahma.

Brahmavaivarta: About protocols of worshipping Devis, Krishna and Ganesha

Garuda: About death and its aftermaths.

Harivamsa: About the origin of Vishnu's incarnation as Krishna

Kurma: About Vishnu’s incarnation as Kurma

Linga: About Shaiva theology

Markandeya: Devi Mahatmya

Matsya: About Vishnu’s incarnation as Matsya (fish)

Narada: About the greatness of Veda and Vedangas.

Padma: About importance of religion, creation theories, about earth, cosmos and also contains a dialogue between Shiva & Parvati

Shiva:  About the god Shiva

Skanda: A meticulous pilgrimage guide, containing geographical locations of pilgrimage centers in India, with related legends, parables, hymns and stories. This is the longest Purana.

Vamana: About North India and areas around Kurukshetra.

Varaha: About rescuing of the earth from Rasatal by Varaha, an incarnation of Lord Vishnu.

Vayu: Measurement of time; origin of gods, sages, daityas, rakshasas, gandharvas and pitrs; origin of animals, birds, trees and creepers; genealogies of the ancient kings; detailed geography of the earth divided into seven dvipas and further sub-divided into the varshas; accounts of inhabitants of different dvipas; names and description of the seven Patalas (netherworlds); description of the solar system and the movements of the celestial bodies; description of the four yugas and fourteen manvantaras.

Vishnu: About creation myths, stories of battles fought between Asuras and Devas, the Avatars (divine descents) of Vishnu, and genealogy and stories of legendary kings.

Bhagvata Purana and Vishnu Purana are probably the most widely known Puranas. Life of Krishna and the Dashavatars of Vishnu are especially popular stories.