https://www.merixstudio.com/blog/laravel-5-tutorial/

• app: this is the heart of our application.
  • HTTP: everything related to accessing our application from the web goes here.
  • Providers: contains providers - classes responsible for loading and management of our application;
• bootstrap: contains Laravel’s initialization files.
• config: this is where our application configuration is placed.
• storage: this is where our application store its data. Make sure to give the app write permission to this folder;