Trios

A trio is a group or set of three members or components. The term can refer to three people working or performing together, or to a work arranged for three performers. It also appears in other contexts to describe a unit composed of three related parts.

In music, a trio denotes both an ensemble and the music they perform. A trio can be a group of three musicians playing together or a composition written for three instruments or voices. Common formats include the string trio (violin, viola, cello), the piano trio (piano with two other instruments, typically violin and cello), and the wind trio. Vocal trios feature three singers. In some musical forms, a trio also refers to a middle section within a larger piece, such as the scherzo-trio structure.

Beyond music, trio has several other uses. In mathematics, a trio denotes a triple or 3-tuple, an ordered collection of three elements. In astronomy, a triple star system describes three stars gravitationally bound to each other. In everyday language, a trio can describe any group of three people or things, such as three friends, colleagues, or co-performers, and is sometimes used in branding or product naming to denote a set of three components.

Etymology traces the word to the Latin tres, meaning three. Related terms include triad, triplet, and triple, which reflect various ways of expressing the concept of three.