Magento\Framework\App implements most of the Magento application framework.

Unlike other components of Magento\Framework that are generic libraries not specific to Magento application, the Magento\Framework\App is "aware of" Magento application intentionally.

The library implements a variety of features of the Magento application:

• bootstrap and initialization parameters
• error handling
• entry point handlers (application scripts):
• HTTP -- the web-application entry point for serving pages of Storefront, Admin, etc
• Static Resource -- for retrieving and serving static content (CSS, JavaScript, images)
• Cron -- for launching cron jobs
• Object manager, filesystem components (inheritors specific to Magento application)
• Caching, cache types
• Language packages, dictionaries
• DB connection configuration and pool
• Request dispatching, routing, front controller
• Services for view layer
• Application areas