Who creates categories?

Categorised in:

There are a great number of categories. Some seem to be duplicated (look in science > space for example). Can anyone create a category or is it just moderators/admins or those that have posted x amount of moots or trusted users (not sure what that is yet)?

All trusted users can create new categories

To be precise: all trusted users, moderators, admins and keyholders can created categories.