In what situations is the MaterialApp widget used in Flutter applications?

In Flutter, the MaterialApp widget is used as the root widget of an application when you need to create an app with Material Design. It provides:

• Theme customization (colors, fonts, etc.)
• Navigation (Navigator)
• Localization
• Route handling
• Other basic features necessary for a Material app

It is used in situations where you need to quickly create an app with a unified style and standard behavior that conforms to Material Design guidelines.

Example of usage:

import 'package:flutter/material.dart';

void main() {
  runApp(MaterialApp(
    title: 'Demo App',
    home: Scaffold(
      appBar: AppBar(title: Text('Main')),
      body: Center(child: Text('Hello, Flutter!')),
    ),
  ));
}