$scope in AngularJS is an object which refers to an application model. It is an object that binds view (DOM element) with the controller. In controller, model data is accessed via $scope object. As we know, AngularJS supports MV* pattern, $scope object becomes the model of MV*.
The $scope is a special JavaScript object. Both View and controller have access to the scope object. It can be used for communication between view and controller. Scope object contains both data and functions. Every AngularJS application has a $rootScope that is the top most scope created on the DOM element which contains the ng-app directive. It can watch expressions and propagate events.