Opus numbers

Opus numbers are a system used to catalog and identify a composer’s musical works. The term "opus" comes from Latin, meaning "work." Each composition is assigned a unique opus number, typically in chronological order of the pieces' publication or composition. For instance, Beethoven’s Symphony No. 5 is referred to as Opus 67. This system helps musicians, scholars, and enthusiasts reference compositions accurately, as many composers have numerous works. However, not all compositions have an opus number, and some may be assigned catalog numbers by later scholars, reflecting varied approaches to categorizing music.