If you are the member of a group that is working on a presentation, or if you are getting your presentation designed by someone else, then you will need to give feedback, without actually editing the slides themselves. Comments are great for such scenarios — a comment is a note that you can attach to any slide object or to a whole slide. The ability to add comments into your PowerPoint presentation enables you to write important notes for particular slide object or for the slide. Once you add a comment in PowerPoint 2011, you can edit the comment and even delete the comment, as explained in the following steps.
Learn how to add, edit, or delete comments within PowerPoint 2011 for Mac.

