Tamil Nadu (lang-ta????????? "Country of the Tamils (Tamil people)", IPA2t??m?? n?a???pronTamil_Nadu.ogg) is one of the 28 states (States and territories of India) of India. Its capital and largest city is Chennai (formerly known as Madras). Tamil Nadu lies in the southernmost part of the Indian Peninsula and is bordered by the States of Puducherry (Pondicherry), Kerala, Karnataka and Andhra Pradesh. It is bound by the Eastern Ghats in the north, the Nilgiri (Nilgiri mountains), the Anamalai Hills, and Palakkad on the west, by the Bay of Bengal in the east, the Gulf of Mannar, the Palk Strait in the south east, and by the Indian Ocean in the south.

Tamil Nadu is the eleventh largest state in India by area (about the size of Greece) and the seventh most populous state. It is the fifth largest contributor to Indias GDP and the most urbanised state in India. The state has the highest number (10.56%) of business enterprises in India, compared to the population share of about 6%. It is one of the foremost states in the country in terms of overall development.

The region has been the home of the Tamil civilization (Tamil people) since at least 1500 BC, as attested by numerous archeological sites in and around Adichanallur. Its classical language Tamil (Tamil language) has been in use in inscriptions and literature for 2500 years. Tamil Nadu is home to many natural resources, grand Hindu temples of Dravidian architecture, hill stations, beach resorts, multi-religious pilgrimage sites and eight UNESCO World Heritage Sites.