Chennai , formerly known as Madras, is the capital of the Indian state of Tamil Nadu. Located on the Coromandel Coast of the Bay of Bengal, Chennai has an estimated population of 7.5 million (2007), making it the fourth largest metropolitan city in India and one of the largest metropolitan areas in the world.

The city was established in the 17th century by the British, who developed it into a major urban centre and naval base. By the 20th century, it had become an important administrative centre, as the capital of the Madras Presidency.

Chennai's economy has a broad industrial base in the automobile, technology, hardware manufacturing, and healthcare industries. The city is home to much of India's automobile industry and is the country's second-largest exporter of information technology and information-technology-enabled services, behind Bangalore.The city is served by an international airport and two major ports; it is connected to the rest of the country by five national highways and two railway terminals. Thirty-five countries have consulates in Chennai.

Chennai is well connected to other parts of India by road and rail. Five major national highways radiate outward towards Mumbai, Kolkata, Trichy, Tiruvallur and Pondicherry. The Chennai Mofussil Bus Terminus (CMBT), the terminus for all intercity buses from Chennai, is the largest bus station in Asia. Seven government-owned transport corporations operate inter-city and inter-state bus services. Many private inter-city and inter-state bus companies also operate services to and from Chennai.

The city has two main railway terminals. Chennai Central station, the city's largest, provides access to trains to major cities like Mumbai, Kolkata, Bangalore, Delhi, Hyderabad, Kochi, Thiruvananthapuram and Coimbatore as well as to smaller towns across India.Chennai Egmore is a terminus for trains traveling primarily within Tamil Nadu; it also handles a few inter-state trains.