Let's start with some definitions. An Article is some written information that you want to display on your site. It normally contains some text and can contain pictures and other types of content.
It is important to understand that the content of the site (article pages, modules, groups, etc.) is totally separate from the visual formatting (template) of the site. It is best to think of text entered in the Administrator Interface as pure content and there is no need to style each individual component.