Musical improvisation is the creation of spontaneous music. Improvisation is often considered an act of instantaneous composition by performers, where compositional techniques are employed with or without preparation. Improvisation is a major part of some types of music, such as blues, jazz, and jazz fusion, in which instrumental performers improvise solos and melody lines. In the Western art music tradition, improvisation was an important skill during the Baroque era and during the Classical era; solo performers and singers improvised virtuoso cadenzas during concerts. However, in the 20th and 21st century, improvisation played a smaller role in Western Art music. In Indian classical music, spontaneous improvisation is a core component and an essential criteria of any performance.