Rock music, sometimes also known as "rock and roll," is a style of music that became popular in the 1950s in America and Europe. It is primarily based on older musical styles, such as the rhythm and blues music originated by African American performers such as Chuck Berry and Little Richard, with a heavy focus on guitar, drums, and powerful vocals.
One of the earliest and most famous performers in the early days of rock was Elvis Presley, who shocked the world with his suggestive dancing and powerful music. He became an instant phenomenon, and led the way for many other performers over the decades to come. In the 1960s, the Beatles were another hugely successful and popular rock music group, also inspired by rhythm and blues songs and by the work of other early British rock performers, such as Cliff Richard.
Over the years, rock music has branched out into a wide variety of styles. Folk rock, such as that made popular by Bob Dylan in the 1960s, often featured acoustic guitars and socially conscious lyrics, many with anti-war sentiments. Psychedelic rock, such as that played by the Grateful Dead, Pink Floyd, and the Doors, featured often dissonant music that was heavily influenced by the use of drugs such as LSD. Progressive rock bands, such as the Moody Blues, Rush, and Yes, experimented with a wide range of instruments, and often included improvisational musical solos that could last for 10 or even 20 minutes.
Rock has also led the way for other music forms, such as heavy metal, which features extreme guitar sound and heavy distortion. Some of the earliest bands that could be classified as heavy metal are Led Zeppelin and Black Sabbath. Both bands started out in the mid-1970s. Their heavy form of music has paved the way for other heavy metal bands, including Metallica and Megadeth.
Today, the term "rock music" is used to refer to a wide range of musical forms, including anything from soft pop to heavy metal. The name has essentially become a default term for any style of music that does not automatically fit into another category, such as R&B, country, or classical. The form has changed significantly since the days of Elvis Presley, but the term can still refer to his songs as easily as they can refer to more recent bands like Nirvana or Pearl Jam.