double bar
Two vertical lines drawn through the staff to indicate the end of a section or the end of a piece
In Depth
A thin double bar marks the end of a section within a piece, signalling a structural boundary without stopping the music. A final double bar (one thin line followed by one thick line) indicates the end of the composition. Double bars often coincide with key changes, tempo changes, or major formal divisions. They serve as visual landmarks that help performers navigate the score and prepare for what comes next.
In orchestral parts, double bars are critical navigation aids — a player who loses their place can scan for double bars to find structural landmarks and re-enter.