The British Indian Army, officially simply the Indian Army, was the principal army of the British Raj in India before independence in 1947. The Indian Army was an important part of the British Empire's forces, both in India and abroad, particularly during the First and Second World Wars.

It was responsible for the defence of both directly governed British India and the Princely States (which could also have their own armies).

The first army officially called the "Indian Army" was raised by the government of India in 1895, existing alongside the three long-established presidency armies (the Bengal Army, the Madras Army and the Bombay Army) of the Presidencies of British India. However, in 1903 the Indian Army absorbed these three armies. The term "Indian Army" was also sometimes used informally as a collective description of the former Presidency armies, particularly after the Indian Mutiny.

The Indian Army should not be confused with the "Army of India" (1903–1947) which was the Indian Army itself plus the "British Army in India" (British units sent to India).

The term British Indian (also Indian British or Indian Britons) refers to citizens of the United Kingdom whose ancestral roots lie in India. This includes people born in the UK who are of Indian descent, and Indian-born people who have migrated to the UK. Today, Indians number around one and a half million in the UK (not including those of mixed Indian and Other ancestry), making them the single largest visible ethnic minority population in the country. They make up the largest subgroup of British Asians, and are one of the largest Indian communities in the Indian diaspora, largely due to the Indian-British relations (including historical links such as India having been under British occupation and still being part of the Commonwealth of Nations). The British Indian community is the fifth largest in the Indian diaspora, behind the Indian communities in Nepal, the United States, Malaysia and Burma.

British Indians are a well established and middle class ethnic group. A study by the Joseph Rowntree Foundation in 2007 found British Indians have among the lowest poverty rates among different ethnic groups in Britain second only to White British.

The Indian Army (IA, Devanāgarī: भारतीय थलसेना, Bhāratīyan Thalasēnā) is the land based branch and the largest component of the Indian Armed Forces.

According to the IISS, in 2010 the army had a strength of 1,129,900 active personnel and 960,000 reserve personnel, making the Indian Army the world's largest standing volunteer army.

Its primary mission is to ensure the national security and defence of the Republic of India from external aggression and threats, and maintaining peace and security within its borders. It also conducts humanitarian rescue operations during natural calamities and other disturbances. The President of India is the Commander-in-Chief of the Army. The Chief of Army Staff (COAS), a General, is a four star commander and commands the army. There is typically never more than one serving general at any given time in the Army. Two officers have been conferred the rank of field marshal, a 5-star rank and the officer serves as the ceremonial chief.

The Indian Army came into being when India gained independence in 1947, and inherited most of the infrastructure of the British Indian Army that were located in post-partition India. The Indian Army is a voluntary service and although a provision for military conscription exists in the Indian constitution, it has never been imposed. Since independence, the army has been involved in four wars with neighbouring Pakistan and one with the People's Republic of China. Other major operations undertaken by the army include Operation Vijay, Operation Meghdoot and Operation Cactus. Apart from conflicts, the army has also been an active participant in United Nations peacekeeping missions.