Flutter has two main types of widgets:

StatelessWidget: Immutable widgets that don't change once built

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text('Hello World');
  }
}

StatefulWidget: Widgets that can change their appearance in response to events

class Counter extends StatefulWidget {
  @override
  _CounterState createState() => _CounterState();
}

class _CounterState extends State<Counter> {
  int count = 0;
  
  @override
  Widget build(BuildContext context) {
    return Text('Count: $count');
  }
}