The Categories API allows components to register new categories with the categories framework. These categories can be selected inside Web Access rules and the Manual classifier as part of web access control policy.
Components that wish to allow users to select from available categories can use the UI-side categories API functions such as CategoriesUISelectCategory and CategoriesUISelectCategories
If you wish to provide classification services that can classify HTTP content, then use the WebActivity API to register an HTTP classifier.
Category Providers
When categories are registered you can optionally register a provider of the category at the same time. A category that has a provider appears in the UI with the provider name next to it so a user can see where the category came from. Additionally, a provided category cannot be deleted by a user and can only be deleted by the original provider.
Category Usage
Components can also register their use of categories (Whether or not they originally provided it) which also appears in the UI, allowing the user to see where a category is being used. Categories that have registered users cannot be deleted manually by the user. This is useful for a component that allows a user to select a category as part of its configuration. The component would then register its use of the category and the user could see that the category was being used by that component.