Understanding how pages, articles, content elements and modules relate to each other is the key to learning Contao. As mentioned before, the site structure is the central element of your website. Visitors of your website always request pages and not articles like in a node-based CMS.
The diagram shows that articles and layouts are the two most important page elements. Whereas articles store the content of a page, the page layout defines how it is displayed on the website. Contao layouts are CSS-based and of course do not use layout tables. The following chapters explain how to create style sheets and modules, how to combine them in a page layout and how to create pages that are using it.