You can use categories to define sections of your site and group related posts. The default category is “Uncategorized” until you change it in your writing section.

When adding a new category on your screen, you’ll fill in the following fields:

• Name — The name is how it appears on your site.
• Slug — The “slug” is the URL-friendly version of the name. It is usually all lowercase and contains only letters, numbers, and hyphens.
• Parent — Categories, unlike tags, can have a hierarchy. You might have a Jazz category, and under that have child categories for Bebop and Big Band. Totally optional. To create a subcategory, just choose another category from the Parent dropdown.
• Description — The description is not prominent by default; however, some themes may display it.

You can change the display of this screen using the Screen Options tab to set how many items are displayed per screen and to display/hide columns in the table.