Keynote's easy to use thanks to the built-in themes that let you start creating slides quickly, and concentrate on their content instead of their layout. Apple's collection of themes offers a good starting point, or you can modify those master slides for your own needs, and do things like change the backgrounds, the fonts, or add a logo or copyright notice. You can also build a theme from the ground up, creating each master slide from scratch.
Each master slide holds a collection of the following preconfigured attributes:
Title and body text box position
Background fill or graphics
Standard bullet styles
Standard object positions for charts , tables, and images
Fills and line styles for shapes and tables
Slide transition style
If you want to modify master slides, you have to first open the normally hidden Master Slides organizer. In the toolbar, click the View button to Show Master Slides, or, in the Navigator, drag the Slides pane separator, as shown in Figure 12-1.