While rock and blues have historically always been closely linked, blues-rock as a distinct genre did not arise until the late 1960s. Blues-rock was characterized by bluesy improvisation, extended boogie jams typically focused on the electric guitar player, and often a heavier, riff-oriented sound and feel to the songs than might be found in traditional Chicago-style blues. The genre was originally British, with artists like Alexis Korner and John Mayall forming groups that acted as a training ground for future stars of the genre such as Free, Savoy Brown and the earliest incarnations of Fleetwood Mac, while American players like Johnny Winter, Paul Butterfield and the group Canned Heat were also pioneers. The virtuoso electric blues playing of Jimi Hendrix (a veteran of many American rhythm & blues and soul groups from the early-mid 1960s) and his power trios - The Jimi Hendrix Experience and Band of Gypsys - has had broad and lasting influence on the development of blues-rock, especially for guitarists.
Blues-rock's best-known artist is probably Eric Clapton, whose work in the mid-60s with The Yardbirds, the supergroup Cream, as well as Derek and the Dominos beginning in 1970 followed by an extensive solo career, have all been seminal in bringing of blues-rock into the mainstream (although blues-rock was just one of the styles those bands played).
In the late 60s Jeff Beck, another former member of The Yardbirds, revolutionised blues rock into a sort of Heavy Rock, taking the UK and the USA by storm with his band, The Jeff Beck Group which had among its members a young Rod Stewart on vocals and an even younger Ronnie Wood on bass. Jimmy Page, a third alumnus of The Yardbirds, went out to form 'The New Yardbirds' which would soon become known as Led Zeppelin. Led Zeppelin was a huge force in the early 70s blues-rock scene but their music soon turned towards hard rock or heavy metal. Other blues-rock musicians influential on the English scene of the 1970s included Rory Gallagher (who was actually Irish) and Robin Trower.
Beginning in the early 1970s, American blues-rock grew to include Southern rock and hard rock bands like the Allman Brothers Band, the James Gang, Stevie Ray Vaughan, Fabulous Thunderbirds and ZZ Top, while - except for the advent of groups such as Foghat (founded by former Savoy Brown members) - the British scene became focused on heavy metal innovation. Blues-rock had a re-birth in the early 1990s and continues to be a smouldering fire with lasting influence today, with many artists such as Tracy Conover, Kenny Wayne Shepherd, The Mods, Jonny Lang, Tommy Castro, Big Sugar, Anthony Gomes, The Black Crowes, The Black Keys, The White Stripes, Joe Bonamassa and Corby Yates performing and releasing albums to enthusiastic fans. Five Horse Johnson is often considered borderlining between acid blues and blues rock, due to their strange guitar riffs.
A classic example of blues-rock is Cream's "Crossroads", adapted from Robert Johnson's "Cross Road Blues" and "Traveling Riverside Blues"; it fuses some of the lyrical and musical styles of blues with rock-styled tempo and guitar solos. Other great examples are found in almost all that Eric Clapton played with The Yardbirds, particularly on their version of Howlin' Wolf's "Smokestack Lightning."