Every presentation you create has its own Slide Master, even if you are not aware. This Master governs the default attributes of all slides in your presentation such as the background, font choices, colors, and even the positioning of the placeholders — this makes all your slides look consistent. However, even then some sets of slides within the same presentation may have disparate slide elements — so you may have some slides that are governed by one Slide Master and other slides that are governed by a completely different Slide Master!
Learn about multiple Slide Masters in PowerPoint 2003 for Windows.

