In order to work on a presentation at the same time, all authors on Windows need to use PowerPoint 2010 or later, or the latest release of PowerPoint Online.
Share your presentation with others and collaborate on it at the same time
Open your PowerPoint presentation, and choose Share in the top-right corner of the ribbon when you're ready to collaborate.
In the Invite people box, enter the email address of the person you'd like to share the presentation with. If you already have the person's contact info stored, you can just enter the name. The drop-down list lets you determine whether your invitees can edit the file or only can view the file.
Click Share. If your file has already been saved to the cloud, an email invitation will be sent to your invitees. If you haven't saved your presentation to OneDrive or SharePoint Online for Office 365, PowerPoint prompts you to do so now. After you do that, the email invitation will be sent.
See where others are working in your shared presentation
Open the presentation and start working in it.
If someone else is viewing or working in the presentation, their thumbnail picture appears in the top-right corner of the ribbon. PowerPoint will alert you when people enter or leave your presentation.
You can instantly chat with the people who are working in the presentation by using Skype for Business. It opens a chat window for instant conversation. Choose the Chat button to start a group chat with everyone working in the document.
Choose Comments to make or view comments. Also, you can reply to or resolve comments and then mark them as complete.
You'll also see the name of anyone viewing or editing the presentation in the Share pane. There's an indicator—on the thumbnail of the slide and in the actual slide—that shows where someone is working in the presentation. Hover over or select that indicator to find out who is editing.
(For accessibility, PowerPoint also allows you to turn on automatic display of the editor's name. Turn it on by doing File > Options > Advanced > Display > Show presence flags for selected items.)
When you’re done working, save your file.
When other authors have made changes, you’ll see the following when you save.
If your updates and other authors’ updates don't conflict, they'll be merged automatically, and you don’t need to do anything else.
Tracking changes: Revisions by others are highlighted
For Office 365 subscribers, PowerPoint 2016 automatically keeps track of changes made in online documents.
On PowerPoint 2016 for Mac, this feature is only available to Office 365 subscribers who have joined the Office Insider program.
When you re-open a changed presentation (or are in a file being actively edited by someone else), changed slides are highlighted in turquoise in the thumbnail pane.
Select a thumbnail to look at the full-size slide. You'll see the changed portion of the slide outlined in turquoise. An accompanying notation tells you who made the change, and when.
(There are some cases where a revised slide is highlighted, but the kind of change that has been made isn't outlined on the individual slide. Examples of such changes include: Changes in the Notes pane, deletion of a shape, addition of a comment, and animation changes.)
What determines whether changes are highlighted:
This feature works on shared documents stored in OneDrive and SharePoint.
Changes are highlighted only when the person who makes the change is using PowerPoint 2016 version 8403 or later.
Changes aren't highlighted if revision data has been turned off for the document in the Trust Center Privacy Options:
If the privacy options aren't turned on, a user's name (and the time when she or he last made edits to an object) are stored in the presentation to support this revision-highlighting feature. Use Document Inspector to remove that info, if necessary. (See the article Remove hidden data and personal information by inspecting presentations for guidance on using Document Inspector.)
If the privacy options are turned on, then this revision highlighting feature is turned off, meaning that no personal data (user names and times mentioned above) is stored.
Data about the read/unread status of individual slides is stored in a separate file on the PC disk under the path %appdata%\Microsoft\PowerPoint\SlideViewState. This location is protected by the Windows Users folder; if you want to, you can manually delete the files that record your own read/unread status.
Changes aren't highlighted if the file is encrypted or password-protected.
Changes aren't highlighted if the file is in .odp format or the older PowerPoint .ppt or .pps format.
Resolve conflicting changes
If there are conflicting changes, a visual comparison between your changes and the conflicting changes from one of your collaborators will pop up when you select Save. You can choose the changes you'd like to keep.
Only changes made by others that directly conflict with changes you've made will show up in the comparison. Non-conflicting changes are merged automatically into your presentation when you save, and you'll see them in the My Changes view.
Choose either My Changes or Changes by Others.
If there is more than one conflict to resolve, do one of the following:
Choose Next to keep resolving conflicts. Choose Previous to revisit an earlier conflict.
If you'd like to choose the same set of changes for all the remaining conflicts, select the Do this for remaining conflicts check box.
When you're done resolving conflicts, choose Done.
The Activity pane lets you see the complete list of changes made so far. It also gives you access to the earlier versions. Choose Activity on the ribbon to see the Activity pane.
Real-time collaboration with auto-save
If you have an Office 365 subscription, you can use real-time collaboration with auto-save. This feature builds on the other work-together features described in this article by allowing you to see what other users are doing (such as typing words) while they are doing it, and by auto-saving all edits that are made. Only one person can work in a particular box at a time. (You'll see a brightly colored border around a box that another user is working in, and there will be a pencil icon and a notation about who is editing it.)
Turn on this feature by going to File > Options > General, and selecting the option under Real-time collaboration options.