Themes are an easy way to design a whole slide show. Every slide in the presentation will change to match the background, font, colors, and effects chosen for each theme.

The good point about themes is that they are easy and quick and make your presentation look nice.

The bad point about themes is that there are only four or five really good ones, and everyone uses them again and again. That is why I would suggest that you do as much of your theme design by yourself as possible--it is better to be original, even if the end design is less professional-looking. You might even go looking on the Internet for more interesting background "wallpaper" images.

As with many design choices in PowerPoint, there is a little button bar on the right side of the themes:

The top two buttons scoll up and down through a list of extra themes. The bottom button with the bigger arrow will show all the themes at one time:

As with most other design elements in Office 2007, there is a live preview as you roll the mouse over the choices.

To the right of the themes, you will note three menus:

Clicking on each of these will modify your theme. First, you can alter the basic colors of a theme:

Second, you can change the fonts:

And third, you can change the effects of objects in the theme:

Note that I have labeled the three objects "Subtle," "Moderate," and "Intense." These are the three basic categories of effects for a shape.

If you recall back to the Home tab, there were several "Quick Styles" you could choose from. The bottom three included these style categories:

In the effects menu, there are three shapes shown in each style choice:

In each of these, the circle shows how the subtle style will change, the arrows shows the moderate, and the rectangle shows the intense style.

Clicking on "Background styles" lets you choose quickly from the styles below:

If you click on "Format Background," you can choose far more detail about the slide background.