What Flutter is
Flutter is Google’s open source SDK for building interfaces for mobile, web, and desktop from a single Dart codebase. The flutter/flutter repository contains the SDK, framework code, toolchain, tests, contributor docs, and development wiki.
The README describes Flutter as a way to craft beautiful, fast user experiences that work with existing code and are used by developers and organizations worldwide. It is a platform, not only a UI kit: Dart, rendering, tooling, and release infrastructure all matter.
How it works
Developers write a widget tree in Dart. Flutter handles rendering and provides one model for state, layout, navigation, and platform integration. That attracts teams that need multiple platforms without rewriting the UI from scratch.
Minimal widget
This shows Flutter’s basic model: UI is composed from nested widgets.
class App extends StatelessWidget {
const App({super.key});
@override
Widget build(BuildContext context) {
return const MaterialApp(
home: Center(child: Text("Hello Flutter")),
);
}
}Why it is popular
Flutter is useful when a team wants a shared visual language, fast prototyping, and control over UI across mobile, desktop, and web directions.
Limits
The limits involve platform size, the Dart ecosystem, platform-specific integrations, and native UX expectations. Apps with deep platform dependencies may still require bridge code and close attention to breaking changes.