Bar Line

The bar line (or barline) is a vertical line drawn through the staff, marking the division between one measure and the next. It is one of the most basic notational elements, organizing the music into rhythmic units (measures or bars).

Bar lines have evolved over centuries. Early Renaissance music had no bar lines; the bar line became a standard notational device during the 17th century as music became more rhythmically structured. By the 18th century, bar lines were essentially universal in Western art music notation.

Variations exist. The single bar line marks routine measure divisions. The double bar line marks the end of a section. The final bar line (heavier, often double) marks the end of the piece. Repeat bar lines (with dots) mark sections to be repeated.

English, descriptive — a ‘bar’ at the end of a measure.

Bar lines mark rhythmic divisions but should not interrupt phrasing. Many phrases cross bar lines; play through the bar line as if it weren’t there, except for the slight rhythmic emphasis on the downbeat.