Avant-garde, jazz, pop, classical, country and western, rock, free, straight-ahead, etc. are ultimately meaningless terms in the face of the music being discussed at best - at worst, those terms often serve as code words for what is in fact a cultural / political discussion more than a musical one.
Pat MethenyFrom 1962 to 1965, the guitar became this icon of youth culture, thanks mostly to the Beatles
Pat Metheny