Summary

A scope is the definitive source for data in AngularJS applications. A scope has direct relationships with the template views, controllers, modules, and services and acts as the glue that binds the application together. A scope also acts as a representation of a database or another server-side data source.

The scope life cycle is linked to the browser event loop so that changes in the browser can change the scope and changes in the scope are reflected in the DOM element that represent them. You can also add custom watch functions that are notified when the scope changes.

Scopes are organized into hierarchies, and the root scope is defined at that application level. Each instance of a controller also gets an instance of a child scope. You can emit or broadcast events from within a scope and then implement handlers that listen for those events and are executed when they are sent.