In addition to customizing the slide master (including working with its preset placeholder boxes, as you just learned), you can fully customize the individual layout masters. This very useful capability is brand new in PowerPoint 2007.
A layout master takes some of its settings from the slide master with which it is associated. For example, by default it takes its background, fonts, color scheme, and preset placeholder positioning from the slide master. But it also can be individually customized; you can override the slide master’s choices for background, colors, and fonts, and you can create, modify, and delete various types of content placeholders.
There are seven basic types of content you can insert on a PowerPoint slide: Text, Picture, Chart, Table, Diagram, Media (video or sound), and Clip Art. A placeholder on a slide master or layout master can specify one of these types of content that it will accept, or you can designate it as a Content placeholder, such that it will accept any of the seven types. Most of the layouts that PowerPoint generates automatically for its themes use the Content placeholder type because it offers the most flexibility. By making all placeholders Content, PowerPoint can get by with fewer separate layout masters because users will choose the desired layout based on the positioning of the placeholders, not their types.
A Content placeholder appears as a text placeholder with a small ...