Why would I add a text box instead of using Outline view to add the text?
The text on the Outline view is either a title or a bulleted item. If you want to place text outside these areas, you must draw a text box. You can draw a text box anywhere on a slide, and you can even overwrite parts of a clip-art image with a text box. Text boxes are useful for describing figures and for placing extraneous notes on your slides.
What if I don't have extensive clip art to embed in my presentations?
PowerPoint comes armed with many images, so you might not need external graphics-art packages. In addition, PowerPoint includes links to the online world so you can search the Internet for clip-art (as well as picture, video, and sound) files.