ELP was one of the biggest and best of the UK's ‘70s prog rock bands. A mighty power trio that placed Keith Emerson's keyboards at the forefront instead of a guitar, the band brought ideas from classical music and jazz into a rock context and pioneered the use of synthesizer. While they could be fearlessly experimental, they also had a strongly melodic, accessible side, exemplified by singer Greg Lake's acoustic ballads, which gave the band some of their biggest hits.