Blues Rock
Blues-rock, as a style in rock music, appeared in 1960s.
The groups "Cream" and "Rollin 'Stones" can be called the primogenators of this style, which have taken blues as a basis in some of their compositions.
To understand what the blues-rock is it has to be heard: try to imagine a blues improvisation with electric guitar with twelve clock harmony.
And play it in tempo rock 'n' roll. If it is difficult to imagine, then it is aurally very melodic and pleasant.