What is a bach opus?

Johann Sebastian Bach, a renowned composer of the Baroque period, is not typically referred to as "bach opus" in classical music. "Bach opus" is not a term used to describe his compositions.

In classical music, an "opus" is a term that indicates a sequential numbering system for a composer's works, usually assigned by the composer or publishers posthumously. For instance, Beethoven's Fifth Symphony is referred to as "Symphony No. 5, Op. 67."

Regarding Johann Sebastian Bach, scholars and musicologists have assigned composition numbers to his works using various catalog systems. The most commonly used catalog for Bach's compositions is the Bach-Werke-Verzeichnis (BWV), compiled by Wolfgang Schmieder in the 20th century. Each of Bach's compositions is identified with a BWV number, such as the "Brandenburg Concertos, BWV 1046-1051," or the "Goldberg Variations, BWV 988."