app.js - Launching point, here we import everything which is required for the app to work, ex: modules, routes, database connection.
/bin/ - Consists of useful executable scripts, default: www, which includes app.js; when invoked starts the node server
/node_modules/ - consists of external modules; which are installed using npm install
package.json - consists of all the modules with their versions and other properties of the application in JSON format
/public/ - Anything here is made publicly available by the server; js, css, images, templates
/routes/ - Backend code
/views/ - All the views, ex: .ejs
/models/ - Database schema; here it will be mongoose schema