Only contributors can annotate and read annotations.
Contributors can annotate any block in a Story, from the read-only view or directly from the editor.
To create a new annotation, click on the bubble that appears on the right when you move your mouse over a block.
You can then start a thread.
Other contributors can then intervene in the thread and provide their point of view. Once the issue is resolved, any contributor can resolve the thread. The thread then disappears.
When you annotate or reply to an annotation in a Story, you then follow the content.
When someone annotates your content (as a contributor), you receive a notification (you can adjust the notifications in the settings).