ng- Controller in Angular Js

<div ng-app="  " ng-controller="  ">

First Name: <input type="text" ng-model="firstName"><br>
Last Name: <input type="text" ng-model="lastName"><br>
<br>
Full Name: {{firstName + " " + lastName}}

</div>

<script>
var app = angular.module('myApp', []);
app.controller('myCtrl', function($scope) {
    $scope.firstName = "  ";
    $scope.lastName = "  ";
});

</script>

In the div ng-app mention your database created app name and cntrl.It displays the names from the database as first name and last name which you provide.