Prism, also known as COMPOSITE Application Guidance/Library, is a framework that ENABLES you to design and develop rich, loosely coupled, flexible, testable, and easy-to-maintain desktop applications, Silverlight Rich INTERNET Applications (RIAs), and Windows Phone applications. Using modular development, the client application can be developed in a way that SIMPLIFIES the complexity of a large application. Applications built with Prism are composed of modules, which are reusable functional units that contain a portion of the application's overall functionality. As modules can be developed, tested, and deployed individually, cross-team DEPENDENCIES can be minimized, and team members can focus on specific aspects of a project.

Major Components of Prism:

• Shell: It serves as a showcase for all modules. You can load all modules here.
• BootStrapper: It is responsible for connecting the modules to Shell.
• Modules: There are reusable functional units that can be developed independently. MVVM design patterns should be used to build these modules.

All the applications modules (A, B, C, and D as shown in the above diagram) are loaded in shell and the bootstrapper is responsible for connecting the modules to the shell.