The Puranas are chronicles and long narratives that popularize the content of the Vedas by appealing to the reader's imagination. There are eighteen Puranas and eighteen Upa Puranas.
Each Purana is distinctly in favour of a particular Deity, whose exploits form its subject matter, and that Deity is considered in that Purana as the Supreme Reality.
Hundreds of special vratas and specialized forms of worship that are practised in different parts of India derive from one or other of these Puranas. The longest Purana is the Skandha Purana (only slightly shorter than the Mahabharata), a Purana dedicated to Lord Subrahmanya or Skandha.