The Nyāya Sūtras are an ancient Indian text on of philosophy composed by Akṣapāda Gautama (also Gotama; c. 2nd century BCE). The sutras contain five chapters, each with two sections. The core of the text dates to roughly the 2nd century, although there are significant later interpolations.

The Nyaya is sometimes called Tarka-Vidyā or the Science of Debate, Vāda-Vidyā or the Science of Discussion. Tarka is the special feature of the Nyāya. Thus some of its features and categories are better understood from that perspective. Gotama is sometimes given the honorific titles "Akṣapāda" (probably in the sense "having his eyes fixed in abstraction on his feet") and "Dīrghatapas" ("performing long penance"). He is also sometimes accorded the religious titles "Ṛṣi" or "Maharṣi".

In the Nyāya Sutras Gotama developed and extended the Vaiśeṣika epistemological and metaphysical system through 528 aphorisms. Later commentaries expanded, expounded, and critically discussed Gotama's work, the first being by Vātsyāyana (c.450–500 CE), followed by the Nyāyavārttika of Uddyotakāra (c. 6th–7th century), Vācaspati Miśra's Tātparyatīkā (9th century), Udayana's Tātparyapariśuddhi (10th century), and Jayanta's Nyāyamañjarī (10th century).