The Document Theme defines the colors, fonts and graphic effects for a document. When applying a Theme you can choose to apply only one, or any number of these elements. All you have to do is select the palette, font or styling from one of the three galleries in the Themes group.

When you open both the font picker and the colour picker, the top entries give you choices that are "theme aware". This means that if you apply your choices to selected text and then change the theme, the applied fonts and colours will be updated. Rather than assigning the colour "green" to content, you are assigning "theme colour 2".The new Office Theme file format (.THMX) is shared between Word, Excel, PowerPoint and Outlook email messages. Almost everything that can be inserted into a document is automatically styled to match the overall document theme creating a consistent document design. Similar themes are also available for data reports in Access and Project or shapes in Visio.The purpose of a theme is to allow the changing of fonts and colors in a consistent way across a document without having to redefine the individual styles. This functionality is lost when you apply a font directly or use one of the Standard colors from the bottom of the color picker, even if you save that information as part of the style definition.In this case the document is no longer "theme-aware".