Madras curry, hot, is a fairly hot curry sauce (with the exception of seafood madras curries, which are made to a slightly different recipe), red in colour and with heavy use of chili powder. Yoghurt is often used to take away some or all of the heat.
Madras curry is said to originate from the south of India, and gets its name from the city known as Madras when English merchants arrived there in 1640 (now Chennai). However, the name 'Madras Curry' is not used in India, but was invented by restaurants in Britain. The spicy Madras curry served in British restaurants is different from authentic Madras curries, with the British variation originating from British Bangladeshi restaurants in the 1970s.