South India is the area encompassing India's states of Andhra Pradesh, Karnataka, Kerala and Tamil Nadu as well as the union territories of Lakshadweep and Pondicherry, occupying 19.31% of area. South India lies in the peninsular Deccan Plateau and is bounded by the Arabian Sea, Indian Ocean and the Bay of Bengal in the west, south and east respectively. The geography of the region is diverse, encompassing two mountain ranges — the Western Ghats and Eastern Ghats and a plateau heartland. Godavari, Krishna, Tungabhadra and Kaveri rivers are important non-perennial sources of water. Inhabitants of South India are referred to as South Indians. A majority of South Indians speak one of the four Dravidian languages — Kannada, Malayalam, Tamil and Telugu. During its history, a number of dynastic kingdoms ruled over parts of South India whose invasions across southern and southeastern Asia impacted the history and cultures of modern nation-states such as Sri Lanka, Indonesia, Thailand and Malaysia. The region was colonised by Britain and gradually incorporated into the British Empire.

After experiencing fluctuations in the decades immediately after Indian independence, the economies of South Indian states have registered higher than national average decadal growth over the past three decades. While South Indian states have improved in some socio-economic metriceseconomic disparity, illiteracy and poverty continue to affect the region much like the rest of the country. Agriculture is the single largest contributor to the regional net domestic product, while Information technology (IT) is a rapidly growing industry. Literary and architectural styles, evolved over two thousand years, differ from other parts of the country. Politics in southern India is dominated by smaller regional political parties rather than by national political parties.

South India is a peninsula in the shape of a vast inverted triangle, bounded on the west by the Arabian Sea, on the east by the Bay of Bengal and on the north by the Vindhya and Satpura ranges. The Narmada flows westwards in the depression between the Vindhya and Satpura ranges. The Satpura ranges define the northern spur of the Deccan plateau. The Western Ghats, along the western coast, mark another boundary of the plateau. The narrow strip of verdant land between the Western Ghats and the Arabian Sea is the Konkan region. The Western Ghats continue south, forming the Malnad (Canara) region along the Karnataka coast, and terminate at the Nilgiri mountains, an inward (easterly) extension of the Western Ghats.

The Nilgiris run in a crescent approximately along the borders of Tamil Nadu with northern Kerala and Karnataka, encompassing the Palakkad and Wayanad hills, and the Satyamangalam ranges, and extending on to the relatively low-lying hills of the Eastern Ghats, on the western portion of the Tamil Nadu - Andhra Pradesh border. The Tirupati and Annamalai hills form part of this range. The low lying coral islands of Lakshadweep are off the south-western coast of India. Sri Lanka lies off the south-eastern coast, separated from India by the Palk Strait and the chain of low sandbars and islands known as Rama's Bridge. The Andaman and Nicobar islands lie far off the eastern coast of India, near the Tenasserim coast of Burma. The southernmost tip of mainland India is at Kanyakumari (Cape Comorin) on the Indian Ocean.