About the directory 'app'

The 'app' folder is basically a base folder where the application sits. Using a single module of an application is good for quick projects but with more complex projects use of Blueprints helps in defining routes and configurations. This folder will have several packages for defining classes for models and forms.

Blueprints are essential components in app which help in organizing projects with several distinct components. There can be different Blueprints for the admin panel, the front-end and for the user dashboard. This helps in sharing the modules, forms and other aspects to group views, static files and templates.