What are categories?
Categories are a way for you to organize your badges by theme. Categories are assigned at the time of creating the badge, and they can be edited later (although that wouldn’t change formerly issued badges). The data about categories shows in reports.
On enterprise sites, categories display on the Available tab. The account owner can elect to have badges display with categories or without.
Categories do not get passed through to the earners. Each earner must establish his or her own categories.
When creating or editing a badge, there are pre populated categories, although you can also create your own.
See also “What are tags?”