Bar lines in music serve to show the beginning and end of measures, which are divisions of time that help musicians and composers keep a steady beat.
What’s a Bar Line?
Bar lines are some of the most important elements in music notation. They divide the music into measures and signal the musician when to play. Bar lines are more than just time-stamps for musicians, though.
Leading a Musician’s Action
They also have a powerful effect on the shape of a composition, and can determine how a musician will interpret the piece.
When playing music with bar lines, musicians use an instinctive interpretation of where to breathe between phrases and sections. This is why bar lines are often called breath marks instead of measure numbers or time stamps.
Not All Bar Lines are Same
Most people assume bar lines are uniform, but they’re actually different from one style of music to another. Bar lines vary depending on the time signature used in the music. A common time signature is “4/4”, which means there are 4 beats per measure, with each beat being a quarter note.