It’s also called a slide master in Microsoft PowerPoint, and it’s basically the slide that sits above all the other slides and as such it controls the visual elements of the theme, such as the layout, background, colours, fonts, and also where these are positioned on any slides you create within that theme.
That way, you can create a consistent look and feel for your presentation.
Beware, there are limitations to how clever the slide master is compared to other publishing software with the same concept of master pages (such as InDesign). In PowerPoint you can’t position elements on the slide master to be on a certain layer (above or below) in relation to elements on the actual slides. But those little niggles are more for your graphic designer to fight with 😂 and hopefully your template will be set up so you can easily work with it to create a consistent look for your brand material.
You can read more about slide masters here at the Microsoft Support site.
Screen cap from Microsoft office support.
I am a brand consultant and conceptual designer. I love using creativity to solve problems for our clients. In my spare time, I like jigsaws and probably a bit of a board game geek.