where and how to use nodejs with angularjs

I am new to UI framework development. Currently my requirement is to work with anuglarjs and nodejs. I know there are few more like me who want to know the exact use..

I am confused as where i need to use nodejs in my application. I tried to find a simple live demo example(plunker/jsfiddle) which used angularjs and nodejs but i couldn't find one.

Currently i have written a small module using angularjs, which hits the java controller class and saves/get the data and display the data on the webpage. Here i'm no where using nodejs. I tried to search in web to understand the use of nodejs with angularjs. Any input's would be very helpful.

Below is the sample javascript code i implemented using angularjs.

myDataCOntroller.js

//some code here

$scope.submitFormData = function(myForm){
        if(myForm.$valid)
         {

            MyDataService.saveOrGetData($scope.myReport).then(
                    function(response) {
                        $scope.myReport = response;
                    },
               function(errResponse){
                   console.error('Errorr');
                });

         }else{
            console.log("invalid form data!!");
         }
    }

myDataService.js

app.factory('myService',function($http,$q,$location){

    var MY_SERVICE_URI = $location.protocol()+'://'+$location.host()+':'+$location.port();

    var _repServiceFactory={};


    _repServiceFactory.saveOrGetData = function(myData){

         var deferred = $q.defer();
         var url = appURL+'/saveOrGetData.form';
         $http.post(url,JSON.stringify(myData))
            .then(
            function (response) {
                   deferred.resolve(response.data);
            },
            function(errResponse){
                console.error('Error while fetching data');
                deferred.reject(errResponse);
            }
        );
        return deferred.promise;
  }

PS: I know that Angularjs is client side, Nodejs is server side, both are using Javascript programming language. What i want to know is, what is the use of nodejs and where is it used in real time??

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