How can I create multiple slides into one Photoshop document?

[EDITS BY TYLER]

 I recently opened a Photoshop template document from Adobe Stock; it was incredibly organized, with multiple different slides that were arranged by number on the top left. How do you get this? 

[D Fosse · Accepted solution]

They are artboards, a function that was added to Photoshop a few years back.

Historically, a Photoshop document could only be a single page. Artboards is a way to allow multiple pages within a single document, often useful for website design. Read more here:

https://helpx.adobe.com/photoshop/using/artboards.html