What is a submission category?
Submissions categories are used to filter applications based on a requirement you may have.
This could be based on proficiency (e.g. emerging, established, senior), a service you provide they might be interested in (e.g. a size for space at a fair - booth, table...) or any other criteria you would like to be able to filter submissions by.
Categories can also be used to only show specific submissions to specific judges. When inviting a judge you will be able to pick which categories they will be able to score on.
Categories are then permanently locked as soon as you get submissions and as soon as you add a judge to your opportunity (judges belong to categories).
If you are expecting a large number of submissions, with many judges, in many categories. We would advice separating your calls into different opportunities, each with their own categories and judges.