Tamilnadu (தமிழ்நாடு) is one of the 28 states of India. Its capital and largest city is Chennai (formerly Madras). Tamil Nadu lies in the southern most part of the Indian Peninsula and is bordered by Puducherry (Pondicherry), Kerala, Karnataka and Andhra Pradesh. It is bound by the Eastern Ghats in the north, the Nilgiri, the Anamalai Hills, and Palakkad on the west, Bay of Bengal in the east, Gulf of Mannar, Palk Strait in the south east and Indian Ocean in the south.

For over 2500 years, the region has been the home of the last surviving classical civilization of the world, the Tamil civilization.It is the homeland of Indian Tamils and their 2500 year old classical language Tamil.

The Tamil culture is as old and comparable to those of other classical civilizations of the world like the Mesopotamian civilization. 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 India's 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. It is home to many natural resources, grand Hindu temples of Dravidian architecture, hill stations, beach resorts, multi-religious pilgrimage sites and three UNESCO World Heritage Sites.

Geography and climate

A semi-arid wasteland near Tirunelveli. Monsoon clouds dump torrents of rain on lush forests that are only a few kilometers away in windward-facing Kerala, but are prevented from reaching Tirunelveli by the Agasthyamalai Range of the Western Ghats (background).Topographic map of Tamil Nadu Tamil Nadu covers an area of 130,058 square kilometres (50,216 sq mi), and is the eleventh largest state in India.

The bordering states are Kerala to the west, Karnataka to the northwest and Andhra Pradesh to the north. To the east is the Bay of Bengal. The southernmost tip of the Indian Peninsula is located in Tamil Nadu. At this point is the town of Kanyakumari which is the meeting point of the Arabian Sea, the Bay of Bengal, and the Indian Ocean. The Western, Southern and the North Western parts are hilly and rich in vegetation.

Tamil Nadu is the only state in India which has both the Western Ghats and the Eastern Ghats and they both meet at the Nilgiri hills. The Western ghats dominate the entire Western border with Kerala, effectively blocking much of the rain bearing clouds of South West Monsoon from entering the state. The Eastern parts are fertile coastal plains and the Northern parts are a mix of hills and plains. The Central and the South Central regions are arid plains and receive less rainfall than the other regions.

Tamil Nadu has a coastline of about 1,000 kilometres (600 mi) which forms about 18% of the country’s coastline (third longest). Tamil Nadu's coastline bore the brunt of the 2004 Indian Ocean Tsunami when it hit India, which left behind 7,793 dead in the state. Tamil Nadu falls mostly in a region of low seismic hazard with the exception of the western border areas that lie in a low to moderate hazard zone. As per the 2002 Bureau of Indian Standards (BIS) map, Tamil Nadu falls in Zones II & III. Historically, parts of this region have experienced seismic activity in the M5.0 range.

Tamil Nadu is heavily dependent on monsoon rains, and thereby is prone to droughts when the monsoons fail. The climate of the state ranges from dry sub-humid to semi-arid. The state has three distinct periods of rainfall:

(1) Advancing monsoon period, South West monsoon (from June to September), with strong southwest winds;
(2) North East monsoon (from October to December), with dominant northeast winds; and
(3) Dry season (from January to May).

The normal annual rainfall of the state is about 945 mm (37.2 in) of which 48% is through the North East monsoon, and 32% through the South West monsoon. Since the state is entirely dependent on rains for recharging its water resources, monsoon failures lead to acute water scarcity and severe drought.

Tamil Nadu is classified into seven agro-climatic zones: north-east, north-west, west, southern, high rainfall, high altitude hilly, and Cauvery Delta (the most fertile agricultural zone). The table below shows the maximum and minimum temperatures that the state experiences in the plains and hills. Tamil Nadu has a wide variety of minerals with the most lignite (almost 90% of India's reserves), magnesite (45%) and garnet (over 40%) reserves in India, among others. Tamil Nadu contributes 15% of the total salt production in the country. Forests cover over 17% of the state's geographical area with several protected areas of Tamil Nadu including wild life and bird sanctuaries.