A movement is a self-contained part of a musical composition or musical form. While individual or selected movements from a composition are sometimes performed separately, a performance of the complete work requires all the movements to be performed in succession. A movement is a section, "a major structural unit perceived as the result of the coincidence of relatively large numbers of structural phenomena."
A unit of a larger work that may stand by itself as a complete composition. Such divisions are usually self-contained. Most often the sequence of movements is arranged fast-slow-fast or in some other order that provides contrast.—Benward & Saker (2009), Music in Theory and Practice: Volume II
Often a composer attempts to interrelate the movements thematically, or sometimes in more subtle ways, in order that the individual movements exert a cumulative effect. In some forms, composers sometimes link the movements, or ask for them to be played without a pause between them.
Liturgical music 
Liturgical works are often made up of many movements, each one intended to be performed at a different place in an act of worship. For instance, in the church tradition, settings of the Mass (examples of which have been composed from the fourteenth century to the present day) often contains a movement for each part of the Ordinary of the Mass.
Classical forms 
Different forms of music that were established during the common practice period have separate conventions about the number of movements required, and their tempo and structure. It was customary for the first movement in a symphony to be allegro and in sonata form, the second andante or adagio, the third a fast scherzo or a Menuett, and the fourth a lively allegro. These conventions were not always strictly followed, however. Examples abound of symphonies from the common practice period that begin or end with a slow movement, or which have three, or even five or more movements. A three-movement version of the symphony form was conventionally used for instrumental concertos, containing only a slow central movement.
In concerts it is, these days, customary to applaud when the entire work is completed, not between movements. During the classical era it was commonplace to applaud after each movement, and individual movements were sometimes encored.
As well as concertos and symphonies, many chamber works also use these forms. These chamber pieces are typically named after the ensemble for which they are written: for example, string quartet, piano trio, wind quintet. As with symphonies there are numerous examples of exceptions to the standard scheme: for example Beethoven's String Quartet op. 131 is in seven movements which are played without any breaks between them.
- Spencer, Peter; Peter M. Temko (1994). A Practical Approach to the Study of Form in Music. Prospect Heights, IL: Waveland Press. p. 31. ISBN 9780881338065. OCLC 31792064. Retrieved May 23, 2012.
- Benward, Bruce; Marilyn Nadine Saker (2009). Music in Theory and Practice 2 (8th ed.). Boston: McGraw-Hill. p. 358. ISBN 9780073101880. OCLC 214305687.