Introduction to widgets

UI

Introduction to widgets

Flutter widgets are built using a modern framework that takes
inspiration from React. The central idea is that you build
your UI out of widgets. Widgets describe what their view
should look like given their current configuration and state.
When a widget’s state changes, the widget rebuilds its description,
which the framework diffs against the previous description in order
to determine the minimal changes needed in the underlying render
tree to transition from one state to the next.

Note:
  If you would like to become better acquainted with Flutter by diving
  into some code, check out basic layout codelab,
  building layouts,
  and adding interactivity to your Flutter app.

Hello world

The minimal Flutter app simply calls the runApp()
function with a widget: