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.