section_path: Creation/Performance
section_name: Performance
paragraph_text: Performance
  
  Performance is the physical expression of music, which occurs when a song is sung or piano piece, guitar melody, symphony, drum beat or other musical part is played. In classical music, a work is written in music notation by a composer and then performed once the composer is satisfied with its structure and instrumentation. However, as it gets performed, the interpretation of a song or piece can evolve and change. In classical music, instrumental performers, singers or conductors may gradually make changes to the phrasing or tempo of a piece. In popular and traditional music, the performers have more freedom to make changes to the form of a song or piece. As such, in popular and traditional music styles, even when a band plays a cover song, they can make changes such as adding a guitar solo or inserting an introduction.
  
  A performance can either be planned out and rehearsed (practiced)—which is the norm in classical music, jazz big bands, and many popular music styles–or improvised over a chord progression (a sequence of chords), which is the norm in small jazz and blues groups. Rehearsals of orchestras, concert bands and choirs are led by a conductor. Rock, blues and jazz bands are usually led by the bandleader. A rehearsal is a structured repetition of a song or piece by the performers until it can be sung or played correctly and, if it is a song or piece for more than one musician, until the parts are together from a rhythmic and tuning perspective.
  
  Many cultures have strong traditions of solo performance (in which one singer or instrumentalist performs), such as in Indian classical music, and in the Western art-music tradition. Other cultures, such as in Bali, include strong traditions of group performance. All cultures include a mixture of both, and performance may range from improvised solo playing to highly planned and organized performances such as the modern classical concert, religious processions, classical music festivals or music competitions. Chamber music, which is music for a small ensemble with only one or a few of each type of instrument, is often seen as more intimate than large symphonic works.