A song is defined as "a type of musical expression in which the human voice plays the primary role and serves as the carrier of a text." Any music that is sung, in general. A piece is described as "a composition, particularly but not always musical." A work includes any product that exists within a system of art such as a painting, sculpture, or theater production. Songs can be performed by a single singer or musician, as in popular music, or by a group, such as jazz songs. Musical pieces often include one or more songs as part of their structure and development. For example, a symphony is a musical piece that usually uses several sections (such as an introduction, a first movement, a second movement, etc.) composed of different types of music: sonata form works are common examples. A cabaret act consists of a series of short pieces played without pause. A ballet is a dramatic performance with music added to it. A conductance is when a performer gives a recital of songs by various composers. The word "song" comes from the Old English gesong, which in turn comes from the Latin cantus, a chanting or singing sound. The term "piece of music" dates back to at least 1450s. It was originally used to describe a vocal melody or chant, but it has since become used to refer to any musical composition.