What tab needs to be opened to apply a transition effect on a slide?

To apply a transition effect on a slide, the Transitions tab must be opened. This tab contains all the tools and options specifically designed for adding and customizing transitions between slides in a PowerPoint presentation. When using the Transitions tab, users can choose from various effects, adjust the timing of the transition, and set options like whether to apply the transition to all slides or just the current one.

Utilizing this tab ensures that users can effectively create visually dynamic presentations that enhance the flow from one slide to the next, engaging the audience and making the presentation more impactful. The other tabs, such as Design, Animations, and Format, are focused on different aspects of presentation design and functionality, but the specific tools for transitions are solely located within the Transitions tab.