Bob Dylan's influence on popular music is incalculable. As a songwriter, he pioneered several different schools of pop songwriting, from confessional singer/songwriter to winding, hallucinatory, stream-of-consciousness narratives. As a vocalist, he broke down the notion that a singer must have a conventionally good voice in order to perform, thereby redefining the vocalist's role in popular music. As a musician, he sparked several genres of pop music, including electrified folk-rock and country-rock. And that's just the tip of his achievements. Dylan's force was evident enough during his height of popularity in the 1960s, but his influence echoed throughout several subsequent generations.