Joomla! articles must be categorized. Generally spoken, categorization is the process of recognizing, differentiating and understanding something through abstraction. This may sound rather complicated but proves very useful when managing several articles.
Joomla! offers the possibility of creating as many categories as you wish. It is possible to build nested categories and an article has to be related to one of these categories.
Newspapers, for example, use categories to better differentiate between their articles. Here is an example from a Joomla! template (Figure 1).
Figure 1: Gavick Template December 2009
They are using the category World News and under this category there are additional categories like Politics, World, War, Disasters and more. Sometimes two levels are sufficient like in this example; sometimes you may need more. In Joomla! 1.5 it was not possible to have more than two levels. With Joomla! 2.5 you can have as many levels as you want. Joomla! no longer has sections - only categories.
In the Category Manager (Administration → Content → Category Manager), you can manage your category tree and filter up to 10 levels (Figure 2).
Figure 2: Category Manager
Like an article, a category consists of a title, a description and many other attributes and options. It can have an additonal image that can be used in different layouts. The image can be selected in the basic settings. A category can also contain images in the description (Figure 3).
Figure 3: Category Edit Form
When you access your Joomla! website you can see exactly these categories in the example data. The navigation uses links to the categories to show all the articles and sub categories (Figure 4). Even the breadcrumb navigation reflects this structure.
Figure 4: Categories as menu links on the website
In the Menu Manager (Administration → Menu → About Joomla!), you can see these menu items, which link to the articles in a category (Figure 5).
Figure 5: Categories as menu links on the website
You can choose from different layouts for the articles. In Figure 5 you can see which layout is used for which link. You can select the layout in the edit form of a menu item (Figure 6).
- a list of all categories
- a blog layout (like on the frontpage)
- a category list
Depending on the layout you have plenty of options to configure the appearance and behavior of sub categories and articles.
Figure 6: Category layouts
A list of all categories
This layout lists all the sub categories from one chosen category (Figure 7).
Figure 7: Layout All Categories
In this case the category description from the top level category Extensions is shown. One level of sub categories with their descriptions is also shown on the page, even empty categories. The articles in the top level category are hidden. Example: Administration → Menus → About Joomla! → Using Extensions → Edit.
A blog layout (like on the frontpage)
The blog layout lists all the articles from one chosen category (Figure 8).
Figure 8: Layout Blog
In this case the category description from the category Components is shown. All the articles related to Components are shown with their teaser text in one column. More columns are also possible. The first seven articles in the top level category are hidden. Example: Administration -> Menus -> Components -> Edit (Figure 9).
Figure 9: Layout Blog settings
A category list
The category list layout lists all the articles from one chosen category in a table structure (Figure 10).
Figure 10: Layout Category List
In this case the category description from the category named Joomla! is shown. All the articles related to Joomla! are shown in a configurable table. You can choose to have parts of the table hidden and various sorting options are available. Example: Administration → Menus → Components → Article Category list → Edit.
The category system introduced is very powerful and easy to use. You can easily structure your entire website by using a set of nested categories in a very user-friendly way. One article can be assigned to one category.