The word Puranam means that which was composed first purvasmin bhutam puranam. There are eighteen Mahapuranams- (Vide This work, III. Vi. 20) They form three groups, namely, sattvika, rajasa and tamasa. The six, Matsya, Kurma, Linga, Siva, Skanda and Agni are tamasa Puranams. The six Brahmanda, Brahmavaivarta, Markandeya, Bhavirya, Vamana and Brahma are rajasa Puranam-s and the six Visnu, Naradiya, Bhagavata, Garuda, Padma and Varaha are sattvika Puranam-s. This classification of the Puranams and other works according to the qualities which prevail in them is found in the Uttara Khanda of Padma Puranam.