"Other types of categories" - That's clear as mud. "Sections are only used for articles. However, categories are also used for other components". But categories are in sections and categories can have other things in them therefore the section that has the category that has "other components" in it also has the "other components" in it. So are sections only for articles or can they also have categories that have other components in them in them? Or am I muddling something simple and obvious by missing some subtlety in the explanation?