There’s no such thing as a single “curry.” In India, the word is used to describe thousands of different spiced sauce dishes that vary by region, season, and cook. The English word “curry” probably comes from the Tamil word kari, which just means a spiced sauce served with rice.
When the British ruled India, they fell in love with the food and brought home a simplified version called “curry powder.” Indian-style curries became hugely popular in Britain, and today a creamy dish called chicken tikka masala - invented by Indian chefs in Britain - is one of the country’s most ordered meals.
Curry travelled even further. British sailors taught the dish to the Japanese in the late 1800s, and Japan turned it into kare-raisu - thick brown sauce over white rice. Today Japanese curry is one of the country’s favorite comfort foods. The same basic idea has become Thai green curry, Caribbean goat curry, and South African bunny chow - each one totally its own thing.