A modular application is an application that is divided into a set of functional units (named modules) that can be integrated into a larger application. A client module encapsulates a portion of the application's overall functionality and typically represents
a set of related concerns. It can include a collection of related components, such as application features, including user interface and business logic, or pieces of application infrastructure, such as application-level services for logging or authenticating
users. Modules are independent of one another but can communicate with each other in a loosely coupled fashion. Modular applications can make it easier for you to develop, test, deploy, and extend your application. Below you will find some resources that complement
the information about this subject on the corresponding
chapter in the Prism MSDN documentation.