In the 1960s, American and British blues and rock bands began to modify rock and roll by adding harder sounds, heavier guitar riffs, bombastic drumming, and louder vocals, from electric blues. Early forms of hard rock can be heard in the work of Chicago blues musicians Elmore James, Muddy Waters, and Howlin' Wolf, The Kingsmen's version of "Louie Louie" (1963) which made it a garage rock standard, and the songs of rhythm and blues influenced British Invasion acts, including "You Really Got Me" by The Kinks (1964), "My Generation" by The Who (1965), "Shapes of Things" (1966) by The Yardbirds and "(I Can't Get No) Satisfaction" (1965) by The Rolling Stones. From the late 1960s, it became common to divide mainstream rock music that emerged from psychedelia into soft and hard rock. Soft rock was often derived from folk rock, using acoustic instruments and putting more emphasis on melody and harmonies. In contrast, hard rock was most often derived from blues rock and was played louder and with more intensity.

Who were three Chicago blues players who influenced hard rock?