1. MVC (Model-View-Controller) pattern
2. Structure
   • app.js is the main entry point of your application
   • server.js imports the app.js and starts the server on port 3000.
   • routes/api/contacts.js API routes.
   • controllers/contacts/... controller function responsible for ...
   • middlewares/ctrlWrapper.js a wrapper middleware function that handles the try-catch block for each controller.
   • models/contacts.js defines the data model for contacts and provides functions to interact with the data
   • services/contacts/... part of the services layer and calls ...
   • schemas/contacts.js - Joi schema for validation