Document categories allow users with many different documents to more easily organize and select based on a unique category. For instance, I may have documents I typically use when recruiting (ie. Resume, Cover Letter, etc) and when hiring (Employee Handbook, Offer Letter, I9 etc). It can be helpful for both organizational and document selection purposes to group those documents within a defined category.
To start, navigate to Document Categories and use the plus sign to create a new.
With your category created, next navigate to Documents to assign your documents to that created category.
Now, when adding a document to a record, you'll have a more easily defined list based on category to choose from to make your selection process quicker.
With your document categories created, you may now wish to create additional documents to affiliate with these categories.