Sub items are sections of content created underneath an item.
An item and its sub items have a parent child relationship. This means all content is part of a hierarchy. Use sub items as much as possible. For example, if you're writing about "fruit” instead of creating a long text writing about all different types of fruit, create sub items (children) under the parent item “fruit” for each type of fruit you write about, e.g. “apples”, “oranges”, etc. By constructing your content this way, it makes it easy for users and search engines to drill down into your content in a logical manner, quickly.