Content plugins run when specific kinds of pages are loaded. They do things ranging from protecting email addresses from harvesters to creating page breaks.
Default on:
The Parks sample site is designed as a simple site that can be routinely updated from the front end of Joomla!.
As a site, it is largely focused on a blog which can be updated using the front end article submission.
New weblinks can also be added through the front end.
A simple image gallery uses com_content with thumbnails displayed in a blog layout and full size images shown in article layout.