Sanskrit literature can be classified under six orthodox heads and four secular heads. They are: (i) Sruti, (ii) Smriti, (iii) Itishasa, (iv) Purana, (v) Agama, (vi) Darsana (vii) Subhashita, (viii) Kavya, (ix) Nataka and (x) Alankara.
The Agamas are theological treaties and practical manuals of divine worship. The Agamas include Tantras, Mantras, and Yantras. These are treatises explaining the external worship of God, in idls, temples, etc. All the Agarmas treat of (i) Knowledge, (ii) Yoga or concentration, (iii) Kriya or making, and (iv) Charya or doing. They also give elaborate details about the ontology, cosmology, liberation, devotion, meditation, philosophy of Mantras, mystic diagrams, charms and spells, temple-building, image-making, domestic observances, social rules and public festivals.
The Agamas are divided into three sections: the Vaisnava, the Saiva, and the Sakta. The three chief sects of Hinduism. viz., Vaishnavism, Saivism, and Saktism, base their doctrines and dogmas on their respective Agamas. The Vaishnava Agamas or Pancharatra Agamas glorify God as Vishnu. The saiva Agamas glorify God as Shiva and have given rise to an important school of philosophy known as Saiva Siddhanta. The Sakta Agamas or Tantra glorify Gad as the Mother of the world under one of the many names of Devi. The Agamas do not derive their authority from the Vedas, but they are not antagonistic to them. They are all Vedic in spirit and character. That is the reason why they are regarded as authoritative.
The Tantra Agamas belong to the Sakta cult. They glorify Shakti as the World-Mother. They dwell on the Shakti (energy) aspect of God and prescribe numerous courses of ritualistic worship of Divine Mother in various forms. There are seventy-seven Agamas. These are very much like the Puranas in some respects. The texts are usually in the form of dialogues between Shiva and Parvati. In some of these, Shiva answers the questions put by Parvati answers, Siva questioning, Mahanirvana, Kularnava, Kulasara, Prapanchasara, Tantraraja, Rudra Yamala, Brahma Yamala, Vishnu Yamala, and Todala Tantra are the important works. The Agamas teach several occult practices, some of which confer powers, while the others bestow knowledge and freedom. Among the existing books the Mahanirvana Tantra is the most famous.