title: what is difference between Data Access layer and service in node.js project structure
body: <p>I'm just starting learning node.js, express and mongoose.
  In some tutorial I see some project structure like they have different folder for controller, different for services , different for data access layer.</p>
  <p>Now my question is what is the difference in services and data access layer file, what we keep there? And where we keep data access layer file in my project structure?</p>
  <p>Also what exactly the task of controller and routes ?</p>