When you're working with others on a shared presentation, everyone with editing permissions will be able to make changes. When someone else is working in the same presentation as you, you'll see what part of the presentation they're working on, and their changes will appear as they make them. Changes you make will likewise be visible to everyone else editing the presentation.
You can add comments to a presentation to give feedback without editing the presentation's contents.
- Select what you want to comment on.
- Click Insert on the menu bar.
- Select Comment.