For implementing organization taxonomy, you use Alfresco Categories, and Content Items such as Documents, Wikis, Blogs, Links etc can be categorized.
However, for finding out content items for a category is a tedious job, you have to use the Share Advanced Search for this. Alternatively, you have to use the Repository Browser.
Also, there is no easy way to search for content items only by category names.
This Add On provides a dedicated page in Share application where you can browse through all the available categories and see corresponding content items under each category.
You can also filter which content items you want to see, for example Documents, Wikis, Blogs, Links etc.