A feature module is an organizational best practice, as opposed to a concept of the core Angular API. A feature module delivers a cohesive set of functionality focused on a specific application need such as a user workflow, routing, or forms. While you can do everything within the root module, feature modules help you partition the app into focused areas. A feature module collaborates with the root module and with other modules through the services it provides and the components, directives, and pipes that it shares.