theme
A theme is a model presentation that includes several slide layouts you can use as a starting point for your own presentation. Themes are designed with coordinating fonts, text styles, colors, and other elements for a unified look.
Most theme layouts include graphic elements like lines, and placeholder text and images that you can replace with your own content. Placeholders make it easy for you to add your own content without having to format it. For example, you can delete placeholders, add more images, text boxes, or other objects, and change theme elements (such as their style). You can also add more slides.
Note: You can’t switch to a different theme after you begin creating your presentation.