The content in Joomla! is the pages of information to be shown on the website.
There are 2 types of content: categorized and uncategorized.
This refers to plain pages that are shown on the website. You can edit these using the back-end, and add as many of them as you want. These pages do not belong to any category hence they are termed as “uncategorized”.
Categorized content also refers to pages, but these pages belong to a structure, which is made up of sections and categories. A section contains different “categories”, which in turn contain pages of content which are also called “content items”.