Bach Opus is a collection of compositions by the German composer Johann Sebastian Bach. The term includes three works: a Fugue, a PARTITA, and a Magnificat. The Fugue is a five-letter composition that is characterized by a theme that is repeated throughout the piece. The PARTITA is a seven-letter work that is composed of several movements and is often used as a dance suite. The Magnificat is a ten-letter composition that is based on the biblical canticle of Mary. All three works are considered to be some of Bach's most important and influential compositions.