It has its roots in 1940s and 1950s rock and roll, rhythm and blues, country music and also drew on folk music, jazz and classical music. The sound of rock often revolves around the electric guitar, bass guitar, drums, and keyboard instruments such as Hammond organ, piano, or, since the late 60s, synthesizers. Rock music typically uses simple unsyncopated rhythms in a 4/4 meter, with a repetitive
snare drum back beat on beats two and four. Guitar solos feature prominently in rock music; however, keyboard, saxophone and blues-style harmonica are also sometimes used as soloing instruments. In its "purest form", it "has three chords, a strong, insistent back beat, and a catchy melody". When it was blended with folk music it created folk rock, with blues to create blues-rock and with jazz, to create jazz-rock fusion. In the 1970s, rock incorporated influences from soul, funk, and Latin music. Also in the 1970s, rock developed a large number of subgenres, such as soft rock, glam rock, heavy metal, hard rock, progressive rock, and punk rock. Rock subgenres that emerged in the 1980s included New Wave, hardcore punk and alternative rock. In the 1990s, rock subgenres included grunge, Britpop, indie rock, and nu metal. A group of musicians specializing in rock music is called a rock band or rock group. Many rock groups consist of an electric guitarist, lead singer, bass guitarist, and a drummer, forming a quartet. Some groups omit one or more of these roles or utilize a lead singer who plays an instrument while singing, sometimes forming a trio or duo; others include additional musicians such as one or two rhythm guitarists or a keyboardist. Rock bands from some genres, particularly those related to rock's foundations in rock and roll, include a saxophone. More rarely, groups also utilize bowed stringed instruments such as violins or cellos, and brass instruments such as trumpets or trombones. In the 2000s, as computer technology became more accessible and music software advanced, it became possible to create high quality music using little more than a single laptop computer. This resulted in a massive increase in the amount of home-produced electronic music available to the general public via the expanding internet and new forms of performance such as laptronica and live coding. These techniques also began to be used by existing bands, as with industrial rock act Nine Inch Nails' album Year Zero (2007), and by developing genres that mixed rock with digital techniques and sounds, including indie electronic, electroclash, dance-punk and new rave. Indie electronic, which had begun in the early 90s with bands like Stereolab and Disco Inferno, took off in the new millennium as the new digital technology developed, with acts including Broadcast from the UK, Justice from France, Lali Puna from Germany and The Postal Service, and Ratatat from the US, mixing a variety of indie sounds with electronic music, largely produced on small independent labels. The Electroclash sub-genre began in New York at the end of the 1990s, combining synth pop, techno, punk and performance art. It was pioneered by I-F with their track "Space Invaders Are Smoking Grass" (1998), and pursued by artists including Felix da Housecat, Peaches, Chicks on Speed, and Ladytron. It gained international attention at the beginning of the new millennium and spread to scenes in London and Berlin, but rapidly faded as a recognisable genre.] Dance-punk, mixing post-punk sounds with disco and funk, had developed in the 1980s, but it was revived among some bands of the garage rock/post-punk revival in the early years of the new millennium, particularly among New York acts such as Liars, The Rapture and Radio 4, joined by dance-oriented acts who adopted rock sounds such as Out Hud. In Britain the combination of indie with dance-punk was dubbed new rave in publicity for The Klaxons and the term was picked up and applied by the NME to bands including Trash Fashion, New Young Pony Club, Hadouken!, Late of the Pier, Test Icicles, and Sh*tdisco forming a scene with a similar visual aesthetic to earlier rave music.
