Category Types
This article will explain the 4 basic options for category types, namely: Discussions, Nested, Flat, and Heading.
In order to obtain the desired user experience on the forum, a category hierarchy will need to be created using a combination of these category types.
For a full explanation of the various settings available when creating categories, view this article: https://success.vanillaforums.com/kb/articles/8-category-configuration-management
Discussions
The default category type, a basic category where users can post discussions. Only categories set to the Discussions type can contain discussions. All other types of categories will not be selectable when choosing where to add a new discussion.
Note that a Discussion category can have subcategories. If this is the case, then users will be able to post discussions in both the parent category, and the (child) subcategories. In most setups, this is not ideal, and you will want to make use of Nested or Flat discussion types to be parent categories.
Nested
Creates a clickable heading that only contains more categories. A Nested category type is used to add subcategories into the Nested category. Note that when a category is set to Nested, it indicates that any subcategories within are Nested. The category which has been set to the Nested type is actually the parent directly. In other words, it is not nested itself.
No discussions can be added directly inside a Nested category. It can only contain it’s subcategories - which, if set to Discussion type, will contain discussions. Nested categories can contain other Nested categories if the forum demands a particularly large organizational structure.
If using the Subcommunities feature, top-level categories must be set to Nested.
Flat
This is a paginated directory structure that can handle thousands of categories. They are sorted alphabetically by default, and cannot be manually arranged.
This is typically only recommended for very large communities with a great deal of categories.
Flat categories have a module that can be inserted into your theme. This will blend right in with your index and list a small number of the categories that the section contains. It has a quick search module, allowing for users to shift through hundreds of categories with ease. This is great for sites that have a large number of products.
To add this to your theme, use this module:{module name="FlatCategoryModule" categoryID=00}
Note that this is not currently available in the Foundation theme. You can find the numerical categoryID in the URL when you are editing a category.
Heading
Unclickable headings that help with forum organization. On the homepage, they will display differently according to your theme. Generally they are bold, and will split your categories into sections:
No content can be added in a ‘Heading’ category - it is used only for organizational purposes.