How does an organ pedalboard expand the notes an organist can play?

The pedalboard expands the musical capabilities of an organ by allowing the organist to play an additional, independent melodic line using their feet. Since the 14th century, this pedal department has functioned similarly to the manual departments (played by the hands) but is designed to control a distinct set of pipes, which are predominantly longer and produce lower pitches.12

By utilizing the feet, an organist can perform more complex music, such as interweaving multiple melodic lines or providing a bass accompaniment to the music played on the manuals. Modern pedalboards typically feature up to 32 notes. Furthermore, the organist can use a coupler to link one or more manual departments to the pedalboard, allowing for the simultaneous sounding of different pipe ranks and greater control over the instrument's overall volume and tonal texture.1