Explain the difference between state stored within the system and systems that do not retain state between requests.

The state maintained within a system (stateful) means that the system stores information about previous interactions or data between requests. This allows the system to remember the user's context, settings, or intermediate results.

In contrast, stateless systems do not store any information between requests. Each request is processed as new and independent, without knowledge of previous ones.

In Flutter, this is manifested as:

• Stateful Widget — a widget that maintains state (e.g., a counter, entered text). When the state changes, the widget is rebuilt, preserving data between updates.
• Stateless Widget — a widget without state, built solely based on input parameters and does not store internal data.

Example:

class CounterWidget extends StatefulWidget {
  @override
  _CounterWidgetState createState() => _CounterWidgetState();
}

class _CounterWidgetState extends State<CounterWidget> {
  int _counter = 0;

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

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

Here, the _counter state is preserved between button presses, which is not possible in a stateless widget.