It is the seventh-largest country by area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world. Bounded by the Indian Ocean on the south, the Arabian Sea on the south-west, and the Bay of Bengal on the south-east, it shares land borders with Pakistan to the west;[d] China, Nepal, and Bhutan to the north-east; and Burma and Bangladesh to the east. In the Indian Ocean, India is in the vicinity of Sri Lanka and the Maldives; in addition, India's Andaman and Nicobar Islands share a maritime border with Thailand and Indonesia.

Home to the ancient Indus Valley Civilisation and a region of historic trade routes and vast empires, the Indian subcontinent was identified with its commercial and cultural wealth for much of its long history. Four world religions—Hinduism, Buddhism, Jainism, and Sikhism—originated here, whereas Zoroastrianism, Christianity, and Islam arrived in the 1st millennium CE and also helped shape the region's diverse culture. Gradually annexed by and brought under the administration of the British East India Company from the early 18th century and administered directly by the United Kingdom from the mid-19th century, India became an independent nation in 1947 after a struggle for independence that was marked by non-violent resistance led by Mahatma Gandhi.

The Indian economy is the world's tenth-largest by nominal GDP and third-largest by purchasing power parity (PPP). Following market-based economic reforms in 1991, India became one of the fastest-growing major economies; it is considered a newly industrialised country. However, it continues to face the challenges of poverty, illiteracy, corruption, malnutrition, inadequate public healthcare, and terrorism. A nuclear weapons state and a regional power, it has the third-largest standing army in the world and ranks seventh in military expenditure among nations. India is a federal constitutional republic governed under a parliamentary system consisting of 28 states and 7 union territories. India is a pluralistic, multilingual, and multi-ethnic society. It is also home to a diversity of wildlife in a variety of protected habitats.

The name India is derived from Indus, which originates from the Old Persian word Hindu. The latter term stems from the Sanskrit word Sindhu, which was the historical local appellation for the Indus River. The ancient Greeks referred to the Indians as Indoi (Ινδοί), which translates as "the people of the Indus". The geographical term Bharat (pronounced [ˈbʱaːrət̪] ( listen)), which is recognised by the Constitution of India as an official name for the country, is used by many Indian languages in its variations. The eponym of Bharat is Bharata, a theological figure that Hindu scriptures describe as a legendary emperor of ancient India. Hindustan ([ɦɪnd̪ʊˈst̪aːn] ( listen)) was originally a Persian word that meant "Land of the Hindus"; prior to 1947, it referred to a region that encompassed northern India and Pakistan. It is occasionally used to solely denote India in its entirety.

India comprises the bulk of the Indian subcontinent and lies atop the minor Indian tectonic plate, which in turn belongs to the Indo-Australian Plate. India's defining geological processes commenced 75 million years ago when the Indian subcontinent, then part of the southern supercontinent Gondwana, began a north-eastward drift across the then-unformed Indian Ocean that lasted fifty million years. The subcontinent's subsequent collision with, and subduction under, the Eurasian Plate bore aloft the planet's highest mountains, the Himalayas. They abut India in the north and the north-east. In the former seabed immediately south of the emerging Himalayas, plate movement created a vast trough that has gradually filled with river-borne sediment; it now forms the Indo-Gangetic Plain. To the west lies the Thar Desert, which is cut off by the Aravalli Range.
The original Indian plate survives as peninsular India, which is the oldest and geologically most stable part of India; it extends as far north as the Satpura and Vindhya ranges in central India. These parallel chains run from the Arabian Sea coast in Gujarat in the west to the coal-rich Chota Nagpur Plateau in Jharkhand in the east. To the south, the remaining peninsular landmass, the Deccan Plateau, is flanked on the west and east by coastal ranges known as the Western and Eastern Ghats; the plateau contains the nation's oldest rock formations, some of them over one billion years old. Constituted in such fashion, India lies to the north of the equator between 6° 44' and 35° 30' north latitude[e] and 68° 7' and 97° 25' east longitude.

The Kedar Range of the Greater Himalayas rises behind Kedarnath Temple, which is one of the twelve jyotirlinga shrines.

India's coastline measures 7,517 kilometres (4,700 mi) in length; of this distance, 5,423 kilometres (3,400 mi) belong to peninsular India and 2,094 kilometres (1,300 mi) to the Andaman, Nicobar, and Lakshadweep island chains. According to the Indian naval hydrographic charts, the mainland coastline consists of the following: 43% sandy beaches; 11% rocky shores, including cliffs; and 46% mudflats or marshy shores.

Major Himalayan-origin rivers that substantially flow through India include the Ganges and the Brahmaputra, both of which drain into the Bay of Bengal. Important tributaries of the Ganges include the Yamuna and the Kosi; the latter's extremely low gradient often leads to severe floods and course changes. Major peninsular rivers, whose steeper gradients prevent their waters from flooding, include the Godavari, the Mahanadi, the Kaveri, and the Krishna, which also drain into the Bay of Bengal; and the Narmada and the Tapti, which drain into the Arabian Sea. Coastal features include the marshy Rann of Kutch of western India and the alluvial Sundarbans delta of eastern India; the latter is shared with Bangladesh. India has two archipelagos: the Lakshadweep, coral atolls off India's south-western coast; and the Andaman and Nicobar Islands, a volcanic chain in the Andaman Sea.

The Indian climate is strongly influenced by the Himalayas and the Thar Desert, both of which drive the economically and culturally pivotal summer and winter monsoons. The Himalayas prevent cold Central Asian katabatic winds from blowing in, keeping the bulk of the Indian subcontinent warmer than most locations at similar latitudes. The Thar Desert plays a crucial role in attracting the moisture-laden south-west summer monsoon winds that, between June and October, provide the majority of India's rainfall. Four major climatic groupings predominate in India: tropical wet, tropical dry, subtropical humid, and montane.