Bar numbers provide crucial reference points in music and make the chronological sequence of music clear. By providing a unique number for each bar, they enable accurate references to specific parts of pieces and allow players to co-ordinate themselves easily in rehearsals and concerts.
In Dorico Pro, bar numbers appear automatically, following the most common practice of showing a bar number at the start of each system in all layouts by default. You can hide and show bar numbers in each layout independently, including showing them at a specified regular interval or in every bar, which is frequently used in film music scores.
The majority of options relating to bar numbers are on the Bar Numbers page in Layout Options. This is because it is very common to display bar numbers differently in different layouts, such as in every bar in full score layouts but only at the start of each system in part layouts.