Can you name the main abstract concepts and components used in Flutter?

In Flutter, the main abstract concepts and components are:

• Widget — the basic building block of the interface. Everything in Flutter is widgets: buttons, text, containers, and even layouts.
• StatefulWidget and StatelessWidget — two types of widgets. StatelessWidget does not hold state, while StatefulWidget can change its state during its lifetime.
• BuildContext — an object that provides access to the widget tree and allows finding parent widgets.
• Element — the link between a widget and a render object, managing the widget's lifecycle.
• RenderObject — responsible for rendering and positioning on the screen.
• State — an object that holds the state of a StatefulWidget.

Example of a simple StatefulWidget:

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

class _CounterState extends State<Counter> {
  int _count = 0;

  void _increment() {
    setState(() {
      _count++;
    });
  }

  @override
  Widget build(BuildContext context) {
    return Column(
      children: [
        Text('Count: \\$_count'),
        ElevatedButton(onPressed: _increment, child: Text('Increment')),
      ],
    );
  }
}