Puranas are the literary genres of the ancient Hindu and Jain literature. They are concerned with the themes of ancient history, geography, religion, tradition, which depict the Indian culture and civilization in a whole. The Puranas represent uniqueness in their composition and are composed in the form of stories recited from one to another. However a number of stories in the Puranas ate compiled and the entire Puranas are classified into two major corpus:- Maha Puranas and the Upa Puranas.

The two Puranas , which are considered to be the main corpus of the Puranas are believed to be written by Vyasa at the end of the Dwapar Age. But the modern scholars deviate from the view and opined that the Puranas were composed from the 4th century BC to the 1st Millennium AD i.e. during the Gupta period. According to these modern scholars the Puranas were composed to popularize the form of religion , the Vedas promoted. Being the post Vedic literatures the Puranas contained the very essence of the Vedas.

The two corpuses of the Puranas i.e. the Maha Puranas and the Upa Puranas are aimed to induce the teachings of the Vedas and devotion to the God in the minds of man.

As mentioned the Puranas are classified into Maha Puranas(greater corpus) and the Upa Puranas( lower Puranas). According to myths and the traditional scriptures, both of these are said to narrate five subjects , namely Sarga (deals with the mystery of Creation), Pratisarga (deals with the process of recreation after dissolution), Vamsha (deals with the genealogy of kings and sages), Manvantara (creation of human races and first human beings) and Vamshanucharita (Dynastic histories).

The Maha Puranas can be classified into the following divisions: - Brahma (depict the creation of the world), Padma (it depicts sage Pulastya describing the religion and true essence of religion to Bhisma and description of cosmos with special reference to Bharat varsa),Vishnu ( considered as Puranratna, it introduced the conception of yugas, battle between the Asuras and the Devas, and the avatars of Lord Vishnu who came to save the world), Bhagavata ( this is concerned with the tales of the exploits and deeds of the Vishnu avatars and the tenth canto narrates the deeds of Lord Krishna as a child), Naradiya (composed as a conversation between sage Narad and Sanat Kumar, this Purana depicts the description of various pilgrimages),Markandeya (composed in a style of a dialogue between the sage Jaimini and the sage Markandeya containing the accounts of the period of human beings and glorify the great goddess. It includes the account of the Puranic genealogies), Agni (includes the description of various incarnations of Vishnu and number of verses dealing with ritual worship, cosmology history, warfare, and even sections on Sanskrit grammar, meter, law, medicine, and martial arts etc. it was recited by Agni to sage Vasistha), Bhavishya ( contains tales signifying the prophecies of future. It also includes legendary stories regarding the royal genealogies ),Brahmavaivarta ( deals with the creation of universe and all beings, relates to description and histories of different goddesses and also the life and deeds of Ganesha and Lord Krishna),Varaha (depicts the exploits of the Varaha as the incarnation of Lord Vishnu, who rescue the earth),Linga (deals with the origin of cosmos, origin of linga, emergence of Brahma and Vishnu. It also includes the teaching of lord Shiva signifying the importance of worship of Linga), Skanda (depicts the life and deeds of the Kartikeya and contain parables, legends and stories, with multiple versions), Vamana ( depicts the stories regarding the Vamana incarnation of Lord Vishnu on earth), Kurma ( deals with the Kurma or the tortoise incarnation of Lord Vishnu, who holds the mainaka mountain in its back during the churning of the sea), Matsya (depicts the story of the Matsya incarnation of Lord Vishnu, who appeared before sage, Manu, a Surya Vamshi and save the world from Rasatal),Garuda (deals with the details of the astronomy, medicine, Grammar, gemstone structure and the qualities. It is a Vaishnava Purana), Brahmanda (containing the detail description of creation of cosmos, discussion of time, details of Kalpa and Yuga, religion and geography, description of dynastic genealogies and Adhyatma Ramayana).

Some Puranas read Shiva in place of Vayu, and Devi Bhagava instead of {Vaishnava) Bhagavata. Shiva is not a Maha Purana; there is also no reason for increasing the traditional number of the Maha Puranas by adding Shiva, Vayu and Harivamsha, as attempted by Pargiter and Farquhar.

However, no uniformity in the enumeration of the Upa Puranas noticed. This is because these Upa Puranas were more sectarian in character, and of a composite nature. Since these Upa Puranas are composed much later of these traditional Maha Puranas, there historical values are less in comparison to the traditional ones. After a thorough consideration the scholars have classified the Upa Puranas into eighteen parts.

The Upa Puranas are classified into following divisions: - Sanatkumar, Narasimha, Nanda, Shivadharma,Durvasa,Naradiya,Kapila,Vamana,Ushanas,Manava,Varuna,Kali Maheshvara, Samba, Saura, Farashara, Maricha, Bhargava etc.

However, RC Hazra, eminent Puranic scholars has collected the names of about a hundred Upa Puranas, of which hardly 15 have appeared in print. Hence these Puranas are mostly in discussion.

The Panchalakshana definition is considered as the standard to determine the date and chronology of the Puranas. The Puranas can be classified into ancient and late according to their degree of conformity to this definition. The less the number of additions to the five characteristics mentioned in the Amarakosha, the older the Purana. Hence judging from this point of view Vayu, Brahmanda, Matsya and Vishnu are considered as the ancient group of Puranas.

The Puranas can also be classified on the preferential basis of the scholars in the alter ages. For this several other facts should be taken into consideration. Such classification are made on the basis which contain all the abstracts of all great works in arts and sciences in Sanskrit, including the usual Puranic materials, such as Garuda, Agni and Narad.. Those which mainly deal with tirthas and vratas such as Padma, Skanda and Bhavishya, can be ascribed to the groups of the traditional Puranas. Brahmanda Puranas can be included in the groups of the historical Puranas. The Linga, Vamana and Markandeya can be categorized in the group of the Sectarian Puranas. The first two are Shaiva Puranas while the last one principally deals with Devi. The revised version of the Old Puranas can be ascribed to the Varaha, Kurma and Matsya.

There are 18 main Puranas and an equal number of subsidiary Puranas or Upa Puranas, according to the modern classification. Hence according to that classification, the most important are the 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 which glorify Vishnu, the symbol of eternity; six are categorized as Rajashik and glorify Brahma, the creator; six are Tamasic and glorify Shiva.

There is a confusion often encountered about the Shiva Purana and the Vishnu Purana. In the Shiva Purana, Lord Shiva is highly eulogized while a secondary position is given to Lord Vishnu. Sometimes Vishnu is belittled and overshadowed in the exaggerated description of the Lord Shiva and his deeds. In Vishnu Purana, Lord Hari is highly eulogized while an inferior status is given to Lord Shiva. Sometimes Lord Shiva is outshine by the magnanimity of the symbol of eternity i.e. Lord Vishnu. This is only to increase the faith of the devotees in their particular Ishta-Devata. However the spiritual devotees always consider Lord Shiva and Lord Vishnu as one. Lord Shiva and lord Vishnu, therefore are considered as the symbol of eternity in different form.

The best among the Puranas are Srimad Bhagavata Purana and Vishnu Purana, according to the chronology of antiquity. The most popular is the Srimad Bhagavata 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 on Navaratri {Durga Puja) days.