Most race directors hire timers. And all timers have scoring software – most commonly RunScore and Race Director. Those packages are typically used to set up things like age groups so that the top 3 runners in an age group are called out in the results.
The example on the right is how RunScore can upload these to RunSignUp.
RunSignUp offers a simple Race Division capability. It allows a race director to set any number of different divisions and mark them by age and gender, as well as set the number of finishers displayed in each division.
This is only used in Results display. When times are uploaded for a participant, since we know their age and gender from registration, we can calculate which division they belong in.
Here is a quick video that explains it and shows you how to set up Divisions: