$rootScope in angularjs

• $rootScope is the parent scope object and it will be single for entire application.
• The data and methods of $rootScope object will be available to all the controllers.
• All $scope objects are child objects of $rootScope.
• The ng-app directive initializes the application.

Example: 

JS :

var MyApp = angular.module("MyApp",[]);

MyApp.controller('DemoRootScope', function ($rootScope) {

    $rootScope.rootScopeName = "Root scope value";

});

MyApp.controller('DemoChildScope', function ($scope,$rootScope) {

    $scope.Name = "scope value";

});

HTML :

    <span class="bi">Sibling Controller1 :</span><br/>

    <div ng-controller="DemoRootScope">

        <span class="b"> Root Scope Name:</span> {{rootScopeName}}

    </div>

    <br/>

    <span class="bi">Sibling Controller2 :</span><br/>

    <div ng-controller="DemoChildScope">

        <span class="b">  Child Scope Name:</span> {{Name}} <br/>

        <span class="b">  Root Scope Name: </span> {{rootScopeName}}

    </div>