What is Rock?
Essentially, rock music is an eclectic mix of a prominent vocal melody accompanied by guitars (usually two―lead and bass, but may include a third 'rhythm guitar'), keyboards, and the drums. Several bands use an innovative mix of piano, saxophone, flute, mandolin, and sitar. The earliest known roots of rock music as a unique genre branching out from rock 'n' roll date back to the early-to-mid 1960s. Over the next 5 decades, it has become one of the most popular and best-selling branches of commercial music.
With the wave of popularity of rock 'n' roll, made immensely popular by the likes of Elvis Presley and the Beatles, two British bands―Pink Floyd and Black Sabbath―founded the sub-genres of progressive rock and heavy metal. Pink Floyd explored a more psychedelic sound combining electric guitars, keyboards, and various miscellaneous sounds to create amazing, unique tonal output, while Black Sabbath delved into a darker, heavier sound.
The next years witnessed an explosion of various subgenres of rock music. The minutest points of contention could lead to the founding of new genres, but the prominent ones, listed below, have endured as major classes of rock.
Numerous branches of rock have been conceived in the last 50-odd years, each with subtle variations. For instance, heavy metal has branched off into progressive, death, acid, dark ambient, power, symphonic, Goth ... the list goes on and on.
Progressive Rock is a very open and intertwined genre of music that got its start in the late 60s, and has carried on to this day. Prog Rock artists try to take the roots of rock and apply to them a more classically influenced structure. The music is often very elaborate, and generally requires exceptional musicians with a great deal of talent. It is not unusual for Prog Rock pieces to be very lengthy; 'Echoes' by Pink Floyd, lasting more than 20 minutes, is an early example of this phenomenon, and the tradition continues to this day in other pieces, such as 'First Light' by Shadow Gallery.
Heavy Metal, as it is currently called, started back in the late '60s. Its emergence is often credited to Black Sabbath. Heavy metal found its roots in the blues and psychedelic music genres, and got its inspiration in the misery of daily life in industrialized cities combined with a fascination for mysticism. The stereotypical metal song combines heavy thudding drums sounds (often with a double bass) with heavily distorted guitar riffs, screaming vocals, and powerful rhythm.
Progressive Metal or Prog Metal is a combination of progressive rock and heavy metal, which came into popularity during the late '80s with Queensryche and Dream Theater. Progressive metal has a small but very loyal and devoted group of fans, who are enthralled by the combination of many unusual elements inherited from the progressive rock tradition such as incorporation of Jazz, orchestration, and other varied influences. Like in Progressive Rock, it is common for pieces to be in excess of 10-15 minutes, and sometimes more, such as the 24-minute 'Octavarium' by Dream Theater.
Hard Rock is a form of rock & roll that finds its roots in the early 1960s garage rock, and draws from jazz, blues, rock and roll, and folk. These diverse influences can be clearly heard in one of the most influential and popular albums of all time, Led Zeppelin IV. AC/DC and Jimi Hendrix are classic examples of early hard rock.
Over the last 50 years, rock has become one of the most popular genres of music, producing numerous iconic artists, who have written the history of rock with their own unique contributions.
Amazingly, several of the above remain as popular as ever, with Pink Floyd drawing record crowds at the Live 8 concert in 2005, and several other bands formed in the 70s releasing albums recently.