Quote:A watermark is a faded background image that displays behind the text in a document. You can use them to indicate a document’s state (confidential, draft, etc.), add a subtle company logo, or even for a bit of artistic flair. PowerPoint doesn’t have a built-in watermark feature like Word, but you can still add them with a text box.

How to Insert a Watermark into PowerPoint

It’s not quite as easy to add watermarks to PowerPoint as it is to Microsoft Word. However, you can add watermark text to the background of individual slides or all slides at once using the Master Slide function.

We’re going to look at how to add watermark text to all slides in a presentation by using the Master Slide feature. If you only want to add watermark text to an individual slide, you can skip the steps for going to the Slide Master.

First, switch to the “View” tab on the PowerPoint ribbon.

Full reading: https://www.howtogeek.com/396425/how-to-use-watermarks-in-powerpoint/