Indian philosophy comprises the philosophical traditions of the Indian subcontinent. There are six schools of orthodox Hindu philosophy—Nyaya, Vaisheshika, Samkhya, Yoga, Mīmāṃsā and Vedanta—and four heterodox schools—Jain, Buddhist, Ājīvika and Cārvāka – last two are also schools of Hinduism. However, there are other methods of classification; Vidyaranya for instance identifies sixteen schools of Indian philosophy by including those that belong to the Śaiva and Raseśvara traditions. Since medieval India (ca.1000–1500), schools of Indian philosophical thought have been classified by the Brahmanical tradition as either orthodox or non-orthodox – āstika or nāstika – depending on whether they regard the Vedas as an infallible source of knowledge.

The main schools of Indian philosophy were formalised chiefly between 1000 BCE to the early centuries of the Common Era. According to philosopher Sarvepalli Radhakrishnan, the earliest of these, which date back to the composition of the Upanishads in the later Vedic period (1000–500 BCE), constitute "the earliest philosophical compositions of the world." Competition and integration between the various schools was intense during their formative years, especially between 800 BCE and 200 CE. Some schools like Jainism, Buddhism, Śaiva and Advaita Vedanta survived, but others, like Samkhya and Ājīvika, did not; they were either assimilated or went extinct. Subsequent centuries produced commentaries and reformulations continuing up to as late as the 20th century. Authors who gave contemporary meaning to traditional philosophies include Swami Vivekananda, Ram Mohan Roy, and Swami Dayananda Saraswati.