Sanskrit literature that is considered to be authoritative by the Hindus can be broadly classified as six orthodox and four secular categories.  The orthodox section contains:

1. Shruti : That which is heard. This is the direct edict of the gods as heard by the Vedic seers. The Vedas fall under this category.
2. Smriti : That which is remembered. These are the law texts, moral stories and the epics written and remembered. These include Sutras and Shastras (e.g. Brahma Sutra and Dharma Shastra). Vedangas (Limbs of Vedas) and Upa-Vedas are also included here.
3. Puranas and upa-Puranas : There are eighteen Puranas of Vyasa and fourteen upa-Puranas.
4. Ithihasas : Mahabharata and Ramayana.
5. Agamas : Texts of ritual and rites of worship.
6. Darsahnas The six philosophical doctrines of salvation.

The secular section has four categories

1. Subhashitas : Wise sayings: Pachatantra and Hitopadesha belong to this category.
2. Kavyas : Scholarly poetry and prose: Kalidasa's Raghuvamsha andKumarasambhava are examples of poetry and Banabhatta's works are the greatest examples of prose literature.
3. Natakas 
   Scholarly dramas: Examples are Kalidasa's Shakunthala and Vishakadatta'sMudrarakshasa.
4. Alankara
   Composition of elegance and ornamental language includes such works as Mammata's Kavyaprakasha and Jagannatha's Rasagangadhara.

The heterodox literatures are those that did not view Vedas as authoritative.  These are Buddhist, Jaina and Charvaka systems.

Orthodox Scriptures 

Shruti 

Vedas are said to be the oldest human literature available. Though there seems to be a long interval between the composition and compilation of the Vedas, there is evidence to suggest that these Vedas, as we know it today was composed around 1500 hundred years before Christ. The English language cognate of the word Vedas is ?Wise?. Because many thinkers composed the Vedas over generations, one can see the transformation of the thought from the earlier polytheistic religion to the later monistic philosophy. The Rig Veda refers to the various deities of the natural phenomena (sun, wind, fire, storm etc.). The Upanishads, which were written later by philosophical thinkers, refers to a monistic theory of Supreme World Soul, namely Brahman. Hinduism, remarkably, has synthesized the various paradoxes of the Vedas into a single religion that is practiced today.

The Vedas contain four main parts: Rig, Sama, Yajur and Atharva. Each Veda has four different parts namely, Samhita (hymns), Brahmana (significance of the hymns), Aranyaka (interpretation) and Vedanta (Upanishad - the metaphysical dialogue). 

The Rig Veda is a collection of hymns praising the gods and glorifying the conquests and the heroics of the aristocratic Aryan cult. There are 1017 hymns in the Rig Veda and these are arranged in ten mandalas or circles. Second to seventh are the oldest and the tenth is the most recent. 

Sama Veda is a collection of certain melodious verses of Rig Veda for the purpose of ceremonial rituals and is not of much importance for philosophical purposes. It is the musical melodies of the passages of Rig Veda used in the ceremonial sacrifices. The Yajur Veda contains sacrificial formulae in prose and verse to be pronounced by the priest. It has two sections, namely White and Black, the latter being more obscure in its meaning. It spells out proper procedures for construction of the altar for ceremonial sacrifices and other rituals. The horse sacrifice, soma sacrifice, agricultural rituals and coronation of kings follow a ceremonial ritual that are explained in theYajur Veda, mainly for the Brahmin class to follow and implement. It also is philosophically unimportant. 

The Atharva Veda consists of mainly magical spells and incantations in verse. In the section called the Bheshanjani, cures using herbs for diseases such as fever, jaundice, dropsy and leprosy are enumerated. Bewitching spells and black magical spells are in the Abhichara section. Atharva Veda was not originally accepted as part of the Shruti Vedas. They seem to contain many popular beliefs and customs practiced by the non-Aryan locals that were later accepted by the aristocracy and the priestly class. Esoteric knowledge dealing with Yantra, Tantra and Mantra are detailed. Yantra is the machine, namely the human body, Mantra is the formula and Tantra is the technique of applying the formulae to the machine to get the best results. The beginning of Indian medical sciences can be found in the Atharva Veda. 

The hymns of the Vedas that are in the form of poetry are called Samhitas. A lengthy appendix of detailed instructions called 'Brahmanas' is part of the Vedas.Brahmanas, written in prose, are commentaries on the four Vedas. They also explain and guide the practices of the customs and sacrifices, often with mythical stories. TheBrahmanas not only give us a glimpse of the social customs of the period but also serve as a transition from the sacrificial Vedas to the more mystical Aranyakas and the Upanishads. 

The Upanishads and the Aranyakas (forest-books) are in turn appendices to the massive Brahmanas. Aranyakas were doctrines meant for sages to study in the forests along with their students. They give insight into early speculation and intellectual discussions that are later seen in more detail in the Upanishads. The concept of the Brahman as the Supreme Being and the soul's (Atman) desire to be immortal is first speculated in the Aranyaka literature. Upanishads are divided into two groups, early and late. Early Upanishads were around the time of Buddha in the sixth century before the Christian era. The late Upanishads are from a period after Buddha. The very essence of spirituality of the Vedas is the Upanishads and Vedanta. The distinction between the two is that the Upanishad is the text and Vedanta is the philosophy. 

While there are numerous Upanishads (1180 to be exact), 108 of them are considered genuine. Isha, Kena, Katha, Mundaka, Taittiriya, Aitareya, Chandogya, Brihadaranyaka and Kaushitaki-Brahmana are considered to be the most significant Early Upanishads. The late Upanishads include Shvetashvatara, Prashna, Mandukya and Mahanarayana. Only these thirteen Upanishads and MaitriUpanishads are considered to be Vedic and important because they have been commented (bhashya) upon by the major teachers (acharyas) of various traditions. Other less important Upanishads are Sabla, Jabala, Paingala (a converswation between Yajnavalkya and his pupil Paingala) and Kaivalya Upanishad. 

Brahma Sutra of Badarayana forms the basis of Vedanta. The doctrines of Vedanta were based on the Upanishads, and gave logical and organized form to their mystical speculations. It maintained that everything in the universe, souls and matter alike, was produced from God's own essence. Vedanta is based on the study of Upanishads, Brahma Sutra and The Bhagavad-Gita (collectively called Prasthana-Traya). The three main systems of Vedanta are Advaita, Vishishtadvaita and Dvaita. The philosophy of Vedanta will be discussed later. A summary of the important Upanishads and the Indian philosophy, as commented by Sarvepalli Radhakrishnan can be referred to in the supplement, at the end of this article.

As already mentioned, the Vedas did not develop as a single document. In its current known form, it perhaps is an accumulation of many centuries of work by many. Yajur Veda, e.g. was compiled a century or two after Rig Veda. The Vedas are timeless and without an author. The Samhita is to be mastered by the Brahmacharis, theBrhamanas are meant for the householders (grahasthashramis), the Aranyakas, which give philosophical interpretations of the Vedas, are intended for Vanaprasthasprior to taking the last stage of Sanyasa ashram. The Upanishads with their sublime, profound, lofty and soul-stirring knowledge help the Sanyasi to gather the knowledge necessary to realize Brahman.

Smriti 

The texts of the Smriti are derived from the Vedas and are hence authentic. Sutras(literally means thread) are manual of instructions in the form of brief aphorisms. Collectively called as Kalpa Sutras they are subdivided into three main Sutras.Srauta Sutras are manuals explaining the scriptures. Grahya Sutras deal with domestic religious ceremonies. Dharma Sutras are manuals of human conduct, the most important of these being attributed to sages Gautama, Baudhayana, Vasishta and Apastamba. Later several prose Sutrsas that are now lost to us were expanded in the form of verses and came to be known as Dharma Shastrsas. The most famous of these Shastras is the Manuva Dharma Shastra of Manu (also called as Manu-Smriti). Others are Smritis of Yajnavalkya and Parasara. Brahma Sutras were written by Badarayana to harmonize the contradictory statements found in the Upanishads and present a uniform higher perception.

In addition there are Vedangas and Upavedas classified under Smriti literature. Vedangas are texts, which augment the Vedas (Limbs of the Vedas). They are necessary for the proper understanding of the Vedas. There are six vedangas namelySiksha Valli (phonetics and pronunciation-from Taittiriya Upanishad), Jyotisha(astronomy, astrology), Kalpa (performance of sacrifice), Nirukti (etymology),Chandas (prosody), and Vyakarana (grammar). Jyotisha is the most famous among them. They are part of the first section (called Valli) of the Taittiriya Upanishads in the Yajur Veda. There are four upavedas (sub-Vedas) namely, Dhanur-veda (military science from the Yajur Veda), Sthapatya-veda (science of construction and mechanics, attached to Atharva Veda), Gandharva-veda (arts and music attached toSama Veda), and Ayur-veda. Ayurveda, also to be found in Atharva Veda deals with health, medicine, is probably the most popular of the upavedas. 


Puranas and Upa-Puranas

The eighteen Mahapuranas are divided into three main groups, namely Brahma Puranas, Vaishnava Puranas and Shaiva Puranas, each containing six texts. 

Brhama Puranas contains Bramha, Brahmanda, Brahma Vaivarta, Markandeya (Devi-mahatmya, Chandi Purana), Bhaivishya and Vamana Puranas. The Vaishnava Puranas are Vishnu, Naradiya, Bhagavata, Garuda, Padma and Varaha Puranas. The Shaiva Puranas include Matsya, Kurma, Linga, Vayu, Skanda and Agni Puranas. Of these Bhagavata and Vishnu Puranas are the most famous. Puranas were created to influence the minds of common man and instill devotion in him with stories of myths and legends of kings and saints. They also make interesting reading and are very popular. There are eighteen upa-Puranas (sub-Puranas) some of which are Surya, Narasimha, Ganesha, Brihannaradiya and Devi-Bhagavata.  

Ithihasa

Ithihasa texts are the famous epics Mahabharata and Valmiki-Ramayana. Less well-known Ithihasa texts are Yogavasistha and Harivamsha. Included in the Mahabharata is the famous Bhagavad-Gita, the epitome of Hindu philosophy. It is also referred to as Gito-Upanishad.  

Agamas

Agamas are texts of rituals and rites in the worship of gods. The Agamas include Mantra, Tantra and Yantras. These are treatises that explain the external, worship of God in the idol, temple etc. The Agamas are divided into three sections namelyVaishnava, Shaiva and Shakta respectively glorifying Vishnu, Shiva and Shakti (Devi). The Agamas do not derive their authenticity from the Vedas but are not antagonistic to them. However, they are not considered as Smriti texts. 

Darshana  

Darshana texts are also called Veda Upangas. There are six schools of philosophy based on the Vedas. They are in the form of short aphorisms and a Rishi is credited with having written each school. Gautama's Nyaya, Kanada's Vaisheshika, Kapila'sSankhya, Patanjali's yoga, Jaimini's Purva Mimamsa and Badarayana's Vedanta-Sutra, (also called as Brahma Sutra or Uttara Mimamsa) are the six doctrines. These are collectively called as Shad-darshana. Nyaya and Vaisheshika literatures together are also classified under the sub heading Tarka Shastra. While Agamaliterature is theological, the Darshana literature is philosophical and logical. TheIthihasa and Puranas are for the masses appealing to their hearts whereas theDarshanas are for the scholars appealing to their intellects.

Secular Scriptures 

There are also Prakarana Granthas. These are considered to be primers or an introduction for spiritual studies. Among them are Atma Bodha, and Bhaja Govindam [also known as Moha Mudhgara]. Besides the scriptures, there arestotra-s and bhajans (devotional songs and hymns) Among the numerous stotras; Sahasranamams (1008 names of each deity) are very famous. Secular literatures include Subhashitas that are wise sayings, Kavyas that are scholarly compositions of poetry. Kavyas written based on the Ithihasa include Meghaduta, Shakuntala andRaghuvamsha by Kalidasa. 

Natakas that are scholarly dramas and Alankara Granthas that are grand compositions of great eloquence and elegance containing ornamental language are also classified as secular literature. The Shrutis are considered to be the foundation of Sanatana Dharma and Hindu Dharma whereas the Smritis form the walls and theIthihasas and Puranas are the buttresses or supports.

All of these scriptures show three definite pathways to follow in the quest of spirituality. They are Karma-kanda (through service) using the Vedangas, Upasana-kanda (through rituals) using the Agamas and Jnana-kanda (through knowledge) studying of the Upanishads. The purpose of the Hindu scriptures is to remove ignorance and make man like God and one with Him. In the Vedas, Samhitas andBrahmanas mainly make up the sacrifices and rituals of the Karma-kanda, whereas the Aranyakas and the Upanishads that deal with knowledge are the Jnana-kandatexts.

Heterodox Literature

The Charvaka, Jaina and Buddhist systems did not respect the authority of the Vedas and are called heterodox systems. The original Charvaka literature on materialism called Brhaspati Sutra (600 B.C.E.) is lost. Glimpses of the doctrine called Lokayat can be obtained from other rival literature of the time, especially Buddhist literature. Madhvacharya in the 14th century summarized the system inSarvadarshanasamgrha. Shankara's Sarvasiddhantasamgrha also discusses the system of Charvaka. The prominence of the materialistic movement can be seen in the famous ancient drama, Prabodha-chandrodaya. The most authentic text of the school is in Tattvopaplavasimha. Significant Jaina literature can be seen in Sri. Umasvati Acharya's Tattvarthadhigama Sutra (after 3rd century C.E.). Mallisena'sSyadvadamanjeri discusses the celebrated Jaina doctrines of Syadvada andSaptabhangi. During the course of development of Buddhism many philosophical schools had their impact on the religion. Chief philosophies of Hinayana are theVaibhashika or direct realism and Sautrantika or indirect realism. The philosophy ofYogachara or idealism and Madhyamika or relativism influenced the Mahayana school. Nagarjuna's (2nd century) Vimshaka and Madhayamika-sutra and Vasubandhu's Vimshatika and Trimshika form the basis of Mahayana philosophy. 

Buddha encouraged his monks to propagate his teachings. After his death Buddhist canon was formulated and transmitted by oral tradition. Many versions were written down several centuries later (2nd and 1st century B.C.E.). The main divisions, calledPitakas (baskets), are Vinaya or monistic rules, the Sutra (in Pali-Sutta, the most important Pitaka) or discourses of Buddha and Abhidharma (in Pali-Abhidhamma) or scholastic metaphysics. Dhammapada (Path of Virtue) is the most famous text ofHinayana Buddhism, perhaps with the exception of Sutta Pitaka. It is an anthology of verses that is part of the Theravada Pali canon scriptures known as Khuddaka Nikaya and contains 423 verses. In addition there are the Jataka, which are stories about Buddha in his previous births, many of which are non-Buddhist in origin. A complete Indian version of the canon is that of the Sri Lanka Theravada School, in Pali language written in 29-17 B.C.E. The Chinese translated the Mahayana writings over a period of thousand years, beginning 1st century C.E. Taisho Daizokyo is a massive 45 volumes of thousand pages each compiled between 1922 and 1933. Tibetan translations began around 7th century C.E. Buddhist historian Busto (1290-1364) translated into two volumes. The first dealt with translation of Buddha's words called Kanjur and the second was translation of the treatises called Tanjur. These together form 320 volumes in Tibetan script, almost a literal, word for word translation of the original Sanskrit version that is now lost.