To read comments that reviewers have added to your presentation, do the following:
On the Review tab, in the Comments group, click Show Markup.
Use the Previous and Next buttons to move between comments.
Tip: In Microsoft PowerPoint 2010, multiple authors can simultaneously work on the same presentation stored on a server, in a process known as co-authoring. To learn more, see the article Work on a presentation at the same time as your colleagues.