The Puranas are the richest collection of mythology in the world. Most of them attained their final form around 500 A.D. but they were passed on as an oral tradition since the time of Krishna (c. 1500 B.C.).
There are eighteen major Puranas and a few minor ones. Each is a long book consisting of various stories of the Gods and Goddesses, hymns, an outline of ancient history, cosmology, rules of life, rituals, instructions on spiritual knowledge. Hence the Puranas are like encyclopedias of religion and culture and contain material of different levels and degrees of difficulty.
The most important Puranas are the VISHNU PURANA, SHIVA PURANA and MARKENDEYA PURANA (to the Goddess). The BHAGAVATA PURANA is important to the worshippers of Krishna. Other Puranas are the Vayu, Agni, Skanda, Kalki, Linga.
The Puranas are perhaps the most important or commonly used scriptural texts of the Hindus. They were guide books for the whole of life and society.
The Puranas are of the same class as the Itihasas (the Ramayana, Mahabharata, etc.). They have five characteristics (Pancha Lakshana), viz., history, cosmology (with various symbolical illustrations of philosophical principles), secondary creation, genealogy of kings, and of Manvantaras (the period of Manuís rule consisting of 71 celestial Yugas or 308,448,000 years). All the Puranas belong to the class of Suhrit-Sammitas, or the Friendly Treatises, while the Vedas are called the Prabhu-Sammitas or the Commanding Treatises with great authority.
Vyasa is the compiler of the Puranas from age to age; and for this age, he is Krishna-Dvaipayana, the son of Parasara.
The Puranas were written to popularise the religion of the Vedas. They contain the essence of the Vedas. The aim of the Puranas is to impress on the minds of the masses the teachings of the Vedas and to generate in them devotion to God, through concrete examples, myths, stories, legends, lives of saints, kings and great men, allegories and chronicles of great historical events. The sages made use of these things to illustrate the eternal principles of religion. The Puranas were meant, not for the scholars, but for the ordinary people who could not understand high philosophy and who could not study the Vedas.
The Darsanas or schools of philosophy are very stiff. They are meant only for the learned few. The Puranas are meant for the masses with inferior intellect. Religion is taught in a very easy and interesting way through the Puranas. Even to this day, the Puranas are popular. The Puranas contain the history of remote times. They also give a description of the regions of the universe not visible to the ordinary physical eye. They are very interesting to read and are full of information of all kinds. Children hear the stories from their grandmothers. Pundits and Purohits hold Kathas or religious discourses in temples, on banks of rivers and in other important places. Agriculturists, labourers and bazaar people hear the stories
There are eighteen main Puranas and an equal number of subsidiary Puranas or Upa-Puranas. The main Puranas are: Vishnu Purana, Naradiya Purana, Srimad Bhagavata Purana, Garuda (Suparna) Purana, Padma Purana, Varaha Purana, Brahma Purana, Brahmanda Purana, Brahma Vaivarta Purana, Markandeya Purana, Bhavishya Purana, Vamana Purana, Matsya Purana, Kurma Purana, Linga Purana, Siva Purana, Skanda Purana and Agni Purana. Of these, six are Sattvic Puranas and glorify Vishnu; six are Rajasic and glorify Brahma; six are Tamasic and they glorify Siva.
Neophytes or beginners in the spiritual path are puzzled when they go through Siva Purana and Vishnu Purana. In Siva Purana, Lord Siva is highly eulogised and an inferior position is given to Lord Vishnu. Sometimes Vishnu is belittled. In Vishnu Purana, Lord Hari is highly eulogised and an inferior status is given to Lord Siva. Sometimes Lord Siva is belittled. This is only to increase the faith of the devotees in their particular Ishta-Devata. Lord Siva and Lord Vishnu are one.
The best among the Puranas are the Srimad Bhagavata and the Vishnu Purana. The most popular is the Srimad Bhagavata Purana. Next comes Vishnu Purana. A portion of the Markandeya Purana is well known to all Hindus as Chandi, or Devimahatmya. Worship of God as the Divine Mother is its theme. Chandi is read widely by the Hindus on sacred days and Navaratri (Durga Puja) days.