In musical notation, a visual symbol consisting of two vertical lines drawn perpendicularly across the staff signifies the end of a section or the entirety of a composition. This symbol, thicker than a standard bar line, visually communicates closure or a significant structural division within the music. It clearly indicates a point of completion for the performer.
The use of this symbol provides a clear demarcation within a score, aiding musicians in understanding the form and organization of the work. Historically, its presence has guided performers and composers in structuring their interpretations and compositions, contributing to clarity and preventing misinterpretations. Its application allows for easier navigation and rehearsal of specific sections within the overall piece.