As mentioned earlier, all articles in Joomla! need to be assigned to categories. You can have as many categories as you want, and you can arrange the categories and subcategories to go as deep as you want. Creating and managing categories is very similar to creating and managing content.
Go to the Content menu, and navigate to Category Manager (or, if you are already in the Article Manager, you can click on the Categories submenu). This will open the Category Manager screen to show the list of all the categories that have already been created. Right now there is just one category, called Uncategorised, as shown in Figure 5.7.
Figure 5.7. Category Manager showing the Uncategorised category
Click on the name Uncategorised and the edit screen for categories will open. It is in most ways similar to the edit screen for an article. You have spaces to insert a title (required), an alias, and a description (optional). The alias will be automatically generated if you leave the field blank, just as for an article. The one important difference is that instead of picking a category, you can pick either No Parent or a parent category. The difference here is that with categories you have the option of creating complex category-subcategory structures. Just as with articles, you should pay attention to the metadata fields for categories. Fill in a metadata description and keywords.
After clicking Save & Close, you will be returned to the Category Manager. Now create some new categories. You can use filler content or create categories that make sense for your site. In our case we created three categories: News, Blog Posts, and Press Releases. In this case, Blog Posts and Press Releases have News as their parent category. Figure 5.8 shows an example of how your Category Manager should look if you have created these categories. Notice how the child categories are visually displayed in relation to the parent category. Altogether people sometimes refer to this structure as the category tree and each set of categories and subcategories as a branch.
Figure 5.8. Category Manager after adding new categories
If you would like to, now would be a good time to write some new articles in these categories.