Angular not defined in node.js app

I'm a node.js novice and after going through a simple tutorial, I've tried to load up an open source application that uses node.js and I'm getting the error below. I'm sure it's a trivial configuration issue, but I'm not seeing it.

ReferenceError: angular is not defined
    at Object.<anonymous> (d:\projects\nodeapp\app\app.js:7:15)
    at Module._compile (module.js:456:26)
    at Object.Module._extensions..js (module.js:474:10)
    at Module.load (module.js:356:32)
    at Function.Module._load (module.js:312:12)
    at Function.Module.runMain (module.js:497:10)
    at startup (node.js:119:16)
    at node.js:906:3

Here is the app.js where the error is occuring.

/**
 * App bootstrap script   <----- START OF FILE
 */

'use strict';

var nodeapp = angular.module('nodeapp', ['ngRoute', 'ngSanitize', 'ngAnimate']);  <----- ERROR

Here is the index.html

<!doctype html>
<html ng-controller="AppCtrl">
<head>
    <meta charset="utf-8">
    <title>App</title>

    <link href="./visual/css/main.css" rel="stylesheet" type="text/css">

    <script src="./bower_components/jquery/jquery.min.js"></script>
    <script src="./bower_components/angular/angular.js"></script>
    <script src="./bower_components/angular-sanitize/angular-sanitize.js"></script>
    <script src="./bower_components/angular-route/angular-route.js"></script>
    <script src="./bower_components/angular-animate/angular-animate.js"></script>

    ... more scripts ...

    <script src="./app.js"></script>

</head>
<body class='app-not-ready'>

    <ng-view></ng-view>

    <div class="notification-bar"
        ng-if="notificationBarVisible"
        ng-animate
        ng-bind="notificationMessage"></div>

</body>
</html>

Here is the folder structure

Folder Structure

You just confused. =) AngularJS is frontend JavaScript framework and work on client side (browser) only. NodeJS is a platform for writing server side. Take a simple example NodeJS application on Express framework. https://github.com/dizel3d/bicycles. First of all you need install NodeJS and it's modules (run in project root directory in command line node i). Start node app.js and open http://localhost:3000.