How is musical composition different from improvisation?

Musical composition is the act of creating a piece of music or the resulting finished product, which is defined by its existence as a repeatable entity. In contrast, improvisation is the extemporaneous or free performance of a musical passage.12

The primary distinction lies in the nature of the musical text:
* Composition: Presumes a tradition where works are fixed and repeatable, often relying on specific musical notation to preserve the integrity of the work.1
* Improvisation: Typically unfolds spontaneously during performance. While it often conforms to stylistic norms, it remains unfettered by the prescriptive features of a specific, fixed musical text.2

Historically, the two are deeply interconnected; many composers used improvisation as a creative warm-up or a method to generate ideas for written compositions. In modern experimental music, the line can blur, as some compositions incorporate indeterminacy, where a composer provides only general instructions or materials, leaving the performer to improvise significant elements of the work.23