Resource Dictionary

A resource dictionary is a keyed dictionary of objects that can be used both in XAML and in code. XAML is the most common usage, particularly for initially defining objects in a resource dictionary.
Resource dictionaries can exist at several positions in an application structure, including as immediate (page) resources, application resources (as part of the application object) or as XAML files that are kept separate and unloaded in the application structure, for later run-time use. Resource dictionaries commonly support two major Silverlight scenarios: defining templates for controls, and defining storyboards for animated properties.
We can change the build properties on the Resource Dictionary from Page to Content or Resource depending on our intentions; Content for Xaml; and Resource for codebehind.