Tamil Nadu (; Tamil: [ˈtamiɻ ˈnaːɽɯ] (listen), abbr. TN) is a state in southern India. It is the tenth largest Indian state by area and the sixth largest by population. Its capital and largest city is Chennai. Tamil Nadu is the home of the Tamil people, whose Tamil language—one of the longest surviving classical languages in the world—is widely spoken in the state and serves as its official language. The state lies in the southernmost part of the Indian peninsula, and is bordered by the Indian union territory of Puducherry and the states of Kerala, Karnataka, and Andhra Pradesh, as well as an international maritime border with Sri Lanka. It is bounded by the Western Ghats in the west, the Eastern Ghats in the north, the Bay of Bengal in the east, the Gulf of Mannar and Palk Strait to the south-east, and the Indian Ocean in the south. The at-large Tamilakam region that has been inhabited by Tamils was under several regimes, such as the Sangam era rulers of the Chera, Chola, and Pandya clans, the Pallava dynasty, and the later Vijayanagara Empire, all of which shaped the state's cuisine, culture, and architecture. After the fall of the Kingdom of Mysore, the British colonised the region and administered it as part of the Madras Presidency, headquartered at the city of Madras, now known as Chennai. After India's Independence in 1947, the Madras State came into existence, whose borders were linguistically redrawn by the States Reorganisation Act, 1956, losing territory to Kerala, Karnataka and Andhra Pradesh. The state was renamed as Tamil Nadu in 1969. It is home to a number of historic buildings, multi-religious pilgrimage sites, hill stations and three World Heritage Sites.The economy of Tamil Nadu is the second-largest in India, with a gross state domestic product (GSDP) of ₹24.85 lakh crore (US$310 billion) and has the country's 11th-highest GSDP per capita of ₹225,106 (US$2,800). It ranks 11th among all Indian states in human development index. Tamil Nadu is the most urbanised state in India, and one of the most industrialised states; the manufacturing sector accounts for more than one-third of the state's GDP. Its tourism industry is the largest among the Indian states. The Tamil film industry plays an influential role in the state's popular culture.

Chennai ( (listen), Tamil: [ˈt͡ɕenːaɪ̯]), formerly known as Madras (the official name until 1996), is the capital city of the Indian state of Tamil Nadu. The state's largest city in area and population as well, Chennai is located on the Coromandel Coast of the Bay of Bengal, and is the most prominent cultural, economic and educational centre of South India. According to the 2011 Indian census, Chennai is the sixth-most populous city in the country and forms the fourth-most populous urban agglomeration. The Greater Chennai Corporation is the civic body responsible for the city; it is the oldest city corporation of India, established in 1688—the second oldest in the world after London. The city of Chennai is coterminous with Chennai district, which together with the adjoining suburbs constitutes the Chennai Metropolitan Area, the 36th-largest urban area in the world by population and one of the largest metropolitan economies of India. The traditional and de facto gateway of South India, Chennai is among the most-visited Indian cities by foreign tourists. It was ranked the 43rd-most visited city in the world for the year 2015 and was ranked the 36th-most visited city in the world for the year 2019. The Quality of Living Survey rated Chennai as the safest city in India. Chennai attracts 45 percent of health tourists visiting India, and 30 to 40 percent of domestic health tourists. As such, it is termed "India's health capital". An established port of trade of British India since the 1600s, Chennai has the fifth-largest urban economy, and had the third-largest expatriate population in India, at 35,000 in 2009, 82,790 in 2011 and estimated at over 100,000 by 2016. Tourism-guide publisher Lonely Planet named Chennai as one of the top ten cities in the world to visit in 2015.Chennai is ranked as a beta-level city in the Global Cities Index, and was ranked the best city in India by India Today in the 2014 annual Indian city survey. In 2015 Chennai was named the "hottest" city (city worth visiting and worth living in for long term) by the BBC, citing the mixture of both modern and traditional values. National Geographic mentioned Chennai as the only South Asian city to feature in its 2015 "Top 10 food cities" list. Chennai was also named the ninth-best cosmopolitan city in the world by Lonely Planet. In October 2017, Chennai was added to the UNESCO Creative Cities Network (UCCN) list for its rich musical tradition. More than one-third of India's automobile industry is based in the city. Home to the Tamil film industry, Chennai is also known as a major film production centre. It is one of the 100 Indian cities to be developed as a smart city under the Smart Cities Mission.