Does a poster get notified if an edit is made to an answer, or should I add a comment to prompt?
Edits that other people make to posts which are yours (both questions and answers) will cause an edit notification to show in your inbox.
However, these notifications are not sent for minor edits. Edits need to be substantiative enough for the system to deem it necessary to notify you. For more information, see Meta.SE:
In order to reduce noise sent to users, we only notify when "substantive" changes are happening on their posts.
There are a few rules in how "substantive" is defined, but typically one of the following should be enough to trigger a message:
- edit to a question title
- the edit in the post body should be over a threshold
- the edit in code sections should be over another threshold
The threshold varies from site to site. Retagging only is not considered "substantive" hence will not send notification.
Notifications are not sent to the user who asked a question if an answer to their question is edited.
The OP should get a notification whenever a non-trivial edit is made to a post.