A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
When you put an application file like a PowerPoint presentation up on the web, it doesn't stream to the user. Instead, their browser downloads a copy of the file to their temp folder and opens it from there. If you want them to view the presentation *as* a PowerPoint file, you have to let them download it in one way or another.
You can apply a password to the presentation so that they can download, open and view it but not edit it.
You can convert it to images so that it's viewable by anyone who can view PPT files, but not editable in any real sense.
But think about what exactly you want to protect against vs what you want to show people.
Consider that anything you show me, I can probably screen-capture at a minimum, so the only real security is not showing it to me in the first place.