The IPS Community Suite uses a "What you see is what you get" (WYSIWYG) editor that allows for rich content in posts. Posts are composed visually - there's no longer any need to use old-fashioned approaches like BBCode.
The editor we use is an extended version of CKEditor, the leading WYSIWYG web editor. As such, you have access to the wide range of plugins and themes available for CKEditor, and you can install them easily to use them in your community. We'll cover how to do that in later steps.
In IP.Board 3, you could create custom BBCode/Media tags. In IPS4, this is now done by creating custom buttons in the editor, which is completely configurable.