Flutter is a cross-platform UI toolkit that is designed to allow code reuse
across operating systems such as iOS and Android, while also allowing
applications to interface directly with underlying platform services. The goal
is to enable developers to deliver high-performance apps that feel natural on
different platforms, embracing differences where they exist while sharing as
much code as possible.

During development, Flutter apps run in a VM that offers stateful hot reload of
changes without needing a full recompile. For release, Flutter apps are compiled
directly to machine code, whether Intel x64 or ARM instructions, or to
JavaScript if targeting the web. The framework is open source, with a permissive
BSD license, and has a thriving ecosystem of third-party packages that
supplement the core library functionality.

This overview is divided into a number of sections:

The layer model: The pieces from which Flutter is constructed.

Reactive user interfaces: A core concept for Flutter user interface
development.