Categories can are created and managed inside the Ubiquity Dashboard but feature inside the app. A category is useful in dividing content into relevant sections for users to easily find what they're after.
By default, all categories are drop-down. A drop-down category will not display all documents in the category on the Library Screen. Instead, it will display the top 2 entries of the category and feature them below the category once tapped.
Unlike the drop-down category (left) the Zoom category feature allows a user to tap a category header and be brought to a new screen that displays all the documents in the category. This feature is great if you have many categories and don't want to congest your Library Screen.