Blues Rock or Blues-rock is a fusion genre of music which combines elements of the blues with rock and roll. It is a particular style developed in the 1960s, a good example being The Rolling Stones who experimented with music from the old Bluesmen like Howlin' Wolf, Muddy Waters and Champion Jack Dupree. (The Rolling Stones later abandoned the style and went on to more classical Chuck Berry style rock.)
Blues rock's best-known artist is probably Eric Clapton, whose work with 60s supergroup Cream, later work with Derek and the Dominos, and extensive solo career have all been seminal in the bringing of blues and rock into the mainstream.
In the late 60s Jeff Beck revolutionised the blues rock into a sort of Heavy Rock, taking the UK and the USA by storm with his band, The Jeff Beck Group with among the members a young Rod Stewart on vocals and an even younger Ronnie Wood on bass.
Blues rock has since been a smouldering fire that still has its influence, see for example The Black Crowes.
While rock and blues have always been historically closely linked, blues-rock as a distinct genre did not arise until the late 1960s. The genre was originally British, with artists like Alexis Korner and John Mayall forming groups that acted as a training ground for the future stars of the genre, while American bands like Canned Heat and the Paul Butterfield Blues Band were also pioneers. Blues-rock was characterized by bluesy improvisation and long jams.
Beginning in the early 1970s, American blues-rock grew to include Southern rock and hard rock bands like the Allman Brothers Band, Stevie Ray Vaughan, Fabulous Thunderbirds and ZZ Top, while the British scene became focused on heavy metal innovation. Blues-rock had a re-birth in the early 1990's and continues today, with many artists such as Kenny Wayne Shepherd, Jonny Lang, Tommy Castro, Anthony Gomes, The Black Crowes and The White Stripes performing and releasing album to enthusiastic fans.