India, more precisely British India, was the most populous colony or imperial possession of the British Empire. Its population greatly exceeded that of settler colonies such as Australia and Canada.
British India included territories ruled directly by Britain as well as a large network of princely states under British paramountcy. At its broadest late-colonial extent, the region encompassed areas that are now India, Pakistan, and Bangladesh. This made it the demographic and political center of the empire.
The East India Company began Britain’s expansion in the subcontinent after victories such as Plassey in 1757. Following the Indian Rebellion of 1857, the Crown assumed direct control in 1858, beginning the British Raj. By 1913, British India had roughly 304 million people, compared with about 412 million people across the entire empire.
India was also central to imperial strategy and finance, which explains the phrase “the jewel in the crown.” However, “India” in this historical question does not mean only the modern Republic of India; it refers to the much larger colonial territory before the 1947 partition and independence.