Merged dictionaries enable you to share resources across applications by combining multiple resource dictionaries.
Consider an example to understand this concept. This example defines a resource dictionary, DictionaryA.xaml, in one application and then makes use of it in another application that also has a local resource dictionary, DictionaryB.xaml, defined in it.
Create a Merged Resource Dictionary
Create a Silverlight Class Library application and add a resource dictionary, DictionaryA.xaml, to it through the Project | Add New Item command.
Add the following markup to the resource dictionary:
<ResourceDictionary xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" ...