In the PowerPoint interface, the area below the Ribbon continues to be tri-paned. These three panes comprise the Slides Pane, the Slide Area, and the Notes Pane. The Slides Pane is the thin strip on the left side of the PowerPoint interface that contains thumbnails of all your slides. Within Normal view, the Slide Pane allows you to move slides easily from one position to the other just by dragging and dropping.
To learn more, choose your version of PowerPoint. If we do not have a tutorial for your version of PowerPoint, explore the version closest to the one you use.