Categories in Joomla provide a method for organizing your content/articles. Here's how it works. Each Category has Articles assigned to it, and some categories may have sub-categories (think parent/child organizational structure). 

Another way to consider this organization is to have a Category called “Pets,” and two sub-categories, one called “Dogs” and one called “Cats.”  Articles about choosing a pet would go under the general category of "Pets". Articles about dogs would be assigned to the “Dogs” sub-category and ones about cats the “Cats” sub-category. You could not have one article that is in both the “Cats” and “Dogs” categories.

Why Use Categories?
There are two main reasons you might want to organize your articles in sections and categories. These are listed here, but will be described in detail in a later document.
  1. List and Blog Layouts
  2. Organizing Articles in Article Manager
Create a Category:
Navigate to the Content menu. In the drop-down list a menu item named Category Manager will appear.  Click it.
Photo of category menu

Once you reach the Category Manager, on the top right you will see several icons.

Click the one marked New to create a new Category.


On the next screen you need to type in a title, and then optionally an alias. 
SUGGESTION: Make the Category title Category 5.
TIP: If you do not add an alias, whatever you put in as the title will become the alias, including unimportant words such as ‘a,’ ‘and,’ and ‘the.’   Failure to add an alias will result in an alias being created for you based upon your category title.

Once you have a title and alias, click "Save & Close."   For example:

After you’ve saved the new category you will be taken to the Category Manager. You can create as many nested categories (or subcategories) as you want.  Let's add one subcategory to our above example.  Within the Category Manager, click on New.  Create a title and and alias. 
SUGGESTION: Title this one "Subcategory 5" 

Under the Details, select the dropdown list beside "Parent."  Choose the parent category from the dropdown list.  For example:

SUGGESTION:  Select "Category 5" as the parent category.

Click on "Save & Close" and you will go back to the Category Manager.  You will notice the category listings are indented in this list by parent/child relationships.