diff --git a/app.js b/app.js
index 5c150ff553..f5cb16f609 100755
--- a/app.js
+++ b/app.js
@@ -11,6 +11,10 @@ var mongoose = require('mongoose');
 var passport = require('passport');
 var expressValidator = require('express-validator');
 
+/**
+ * Create Express server.
+ */
+
 var app = express();
 
 /**
@@ -112,6 +116,11 @@ app.get('/api/aviary', apiController.getAviary);
 app.get('/api/paypal', apiController.getPayPal);
 app.get('/api/paypal/success', apiController.getPayPalSuccess);
 app.get('/api/paypal/cancel', apiController.getPayPalCancel);
+
+/**
+ * OAuth routes for sign-in.
+ */
+
 app.get('/auth/facebook', passport.authenticate('facebook', { scope: 'email' }));
 app.get('/auth/facebook/callback', passport.authenticate('facebook', { successRedirect: '/', failureRedirect: '/login' }));
 app.get('/auth/github', passport.authenticate('github'));
@@ -120,6 +129,11 @@ app.get('/auth/google', passport.authenticate('google', { scope: 'profile email'
 app.get('/auth/google/callback', passport.authenticate('google', { successRedirect: '/', failureRedirect: '/login' }));
 app.get('/auth/twitter', passport.authenticate('twitter'));
 app.get('/auth/twitter/callback', passport.authenticate('twitter', { successRedirect: '/', failureRedirect: '/login' }));
+
+/**
+ * OAuth routes for API examples that require authorization.
+ */
+
 app.get('/auth/foursquare', passport.authorize('foursquare'));
 app.get('/auth/foursquare/callback', passport.authorize('foursquare', { failureRedirect: '/api' }), function(req, res) {
   res.redirect('/api/foursquare');