Improvisation in music is the act of spontaneously creating new melodies, harmonies or rhythms within the scope of an existing composition. Jazz music relies heavily on improvisation, but nearly every type of music makes use of improvisation by the performer. The importance of improvisation varies based on the particular type of music.
The major traditions of Indian classical music, Carnatic and Hindustani, both rely on improvisation. Musicians improvise nearly all of the music when performing a raga, which is a series of notes used as a framework for a single performance. Raga performances must reflect the time of day, season and mood of the audience in their improvisation, and can therefore be different each time a musician performs.
Folk and Street
Many forms of folk music from around the world incorporate improvisation into their performances. Examples include Gypsy musicians in Europe and the Middle East and fiddle and banjo players in early American rural life. Street musicians often improvise the lyrics to music they perform, such as corridos in Mexico or freestyle raps in urban areas of the United States and Canada. Musicians perform many such songs differently each time because the songs move from performer to performer aurally, without a written version to rely on.
Improvisation once played a larger role in Western classical music than today. Composers included fewer details in their scores until the 19th century and expected performers to interpret their compositions more freely. Mozart, Beethoven and Bach all performed improvised music during their lifetimes. The cadenza, a specified portion of a classical composition that is not written out and thus must be improvised, is the only remaining vestige of this tradition.
Rock music incorporates improvisation in several ways. Psychedelic rock music in the 1960s and 1970s featured musicians who performed extended guitar solos that lasted more than 10 minutes at a time, while the typical rock song is three to five minutes long. The Grateful Dead incorporated longer improvisations into their live concerts, during which the entire band would improvise for up to an hour or longer. The “jam band” subgenre of rock music includes bands whose performances often include extended improvisations over a set rhythm or chord progression.