Categories
Group related Posts into broad subjects.
Categories give Posts a stable high-level structure and can have their own archive pages.
When to use a Category
Use Categories for the main subjects readers are likely to browse. A small, deliberate set is usually easier to understand than dozens of overlapping Categories.
Create and edit
Open Content → Categories to add, rename or edit a Category. Check the public route before changing a Category already in use.
Assign Posts
Choose the relevant Categories from the Post editor. A Post may belong to more than one Category when that genuinely helps browsing.