Music is the art of arranging sound. It is one of the universal cultural aspects of all human societies. Music may be defined with styles that emphasize, de-emphasize, or omit common elements of organized sound, such as rhythm, volume and pitch. Rhythm may be specified with tempos, sometimes organized using meters, and often coordinating the variation and juxtaposition of pitch. Individual sounds possess timbres or texture, which heavily contribute to the music's overall character. A musical ensemble, also known as a music group or musical group, is a group of people who perform instrumental or vocal music, with the ensemble typically known by a distinct name. Some music ensembles consist solely of instrumentalists, such as the jazz quartet or the orchestra. Other music ensembles consist solely of singers, such as choirs and doo wop groups. In both popular music and classical music, there are ensembles in which both instrumentalists and singers perform, such as the rock band or the Baroque chamber group for basso continuo and one or more singers. In classical music, trios or quartets either blend the sounds of musical instrument families (such as piano, strings, and wind instruments) or group together instruments from the same instrument family, such as string ensembles (e.g., string quartet) or wind ensembles (e.g., wind quintet). Some ensembles blend the sounds of a variety of instrument families, such as the orchestra, which uses a string section, brass instruments, woodwinds and percussion instruments, or the concert band, which uses brass, woodwinds and percussion.A musical instrument is a device created or adapted to make musical sounds. In principle, any object that produces sound can be considered a musical instrument—it is through purpose that the object becomes a musical instrument. A person who plays a musical instrument is known as an instrumentalist. The history of musical instruments dates to the beginnings of human culture.