Rock music is a style of music derived from the blues, characterised by a prominent drum beat in 4:4 time, accompanied by electric bass guitar providing the harmonic underpinning for the melody of electric guitar and vocals.
Elvis Presley and Buddy Holly were early pioneers of Rock in the late 1950s, as were the Beatles and Rolling Stones throughout the 1960s. During the aforementioned 1960's an experimental type of rock known as psychedelic rock became popular. In the 1970's it was replaced by progressive rock which removed a lot of the influence that psychoactive drugs had had on psychedelic rock and replaced them with influences from other musical genres such as jazz. Later progressive rock started to decline in popularity, and a new style called Punk rock became popular. In the 80s, New wave showed up and became popular as well. By the latter half of that decade, Glam rock had stultified into MTV-friendly "hair metal", and the stage was set for Nirvana and the Seattle scene, a darker and heavier rock subgenre known as Grunge. By 1994 and the death of Kurt Cobain, grunge had changed into the stable formula of alternative rock that continues to be popular today. Traditional rock music is rare in modern times, having been almost entirely replaced by alt and Indie rock.