Flutter Fundamentals

Flutter lets you build applications for mobile, web, and desktop from a shared Dart codebase. You describe the interface as a tree of widgets. Flutter turns that description into pixels, handles input, and connects the application to the host platform.

This course gives you a working map of that system. You will understand where Dart, widgets, state, rendering, packages, and platform code fit. You will also see where shared code helps and where a platform still needs dedicated work.

The central model

Flutter is a reactive, declarative user-interface framework. Declarative means you describe the interface that should exist for the current application state. When the state changes, Flutter rebuilds the affected widget descriptions and updates the rendered interface.

A widget is an immutable description of part of the interface. Text, padding, alignment, layout, gestures, themes, and navigation all use widgets. You combine focused widgets into a widget tree instead of configuring one large screen object.

The build method returns part of that tree. Its BuildContext identifies a widget's location in the tree. Flutter uses that location to resolve nearby information such as themes and navigation.