fourpart

Fourpart, or four-part, is a term used to describe a structure or composition divided into four distinct parts or voices. In music, it most often refers to four-part writing for voices or instruments, in which each part forms its own melodic line. The arrangement is common in Western music and is the basis of many four-voice choral textures. The term is usually spelled four-part, but fourpart appears less commonly as a stylized form or in titles.

In four-part harmony, the standard configuration is soprano, alto, tenor, and bass, though parts may be redistributed for range or timbre. Composers follow voice-leading conventions to avoid parallels and to maintain balanced voices. While most associated with choral music, four-part writing also appears in instrumental ensembles that require four independent parts.

Historically, four-part writing became a dominant approach during the Renaissance and Baroque periods, refined in the common-practice era. It underpins many hymn tunes, motets, and sacred chorales, and continues in contemporary choral arrangements and simplified SATB settings for education.

While "fourpart" is largely a musical term, it can also describe any work or structure organized into four components in other fields, though in those contexts, the hyphenated form "four-part" is more common.

Related topics include four-part harmony, SATB, choral music, polyphony, and voice leading.