Blues-rock is a hybrid musical genre combining bluesy improvisations over the 12-bar blues and extended boogie jams with rock and roll styles. The core of the blues rock sound is created by the electric guitar, bass guitar and drum kit, with the electric guitar usually amplified through a tube guitar amplifier, giving it an overdriven character. It is a style of rock music with roots in electric blues. Blues rock was the origin of the hard rock and heavy metal genres.