Flutter, developed by Google, is a popular open-source UI framework for building natively compiled applications for mobile, web, and desktop from a single codebase. It enables developers to create beautiful and high-performance apps for iOS, Android, and the web with a single codebase. In this tutorial, we'll walk through the process of getting started with Flutter and building a simple cross-platform mobile app.

Before we get into this article, if you want to learn more on Flutter, I would recommend the tutorials over at Educative, who I chose to partner with for this tutorial.

Prerequisites

Before we begin, ensure that you have the following tools and knowledge:

1. Flutter SDK installed on your system. You can download it from the official website: https://flutter.dev/docs/get-started/install.

2. An integrated development environment (IDE) like Visual Studio Code (recommended) or Android Studio with the Flutter plugin installed.

3. Basic knowledge of Dart, the programming language used by Flutter.

Step 1: Setting Up Flutter

Let's start by setting up Flutter on your system:

1. Install Flutter by following the official installation guide: https://flutter.dev/docs/get-started/install.

2. Verify your installation by running the following command:
   

   flutter doctor

This command will check for any issues with your Flutter installation and provide recommendations to resolve them.

Step 2: Creating a New Flutter Project

Now that Flutter is set up, let's create a new Flutter project:

1. Open your terminal and run the following command to create a new Flutter app:

   flutter create my_first_flutter_app

Replace my_first_flutter_app with your preferred project name.

1. Navigate to the project directory:

   cd my_first_flutter_app

Step 3: Building the App

Let's build a simple counter app to get started:

1. Open the lib/main.dart file in your project directory. This is the entry point for your Flutter app.

2. Replace the existing code with the following:
   

   import 'package:flutter/material.dart';

   void main() {
     runApp(MyApp());
   }

   class MyApp extends StatefulWidget {
     @override
     _MyAppState createState() => _MyAppState();
   }

   class _MyAppState extends State<MyApp> {
     int _counter = 0;

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

     @override
     Widget build(BuildContext context) {
       return MaterialApp(
         home: Scaffold(
           appBar: AppBar(
             title: Text('Flutter Counter App'),
           ),
           body: Center(
             child: Column(
               mainAxisAlignment: MainAxisAlignment.center,
               children: <Widget>[
                 Text(
                   'Counter:',
                   style: TextStyle(fontSize: 24),
                 ),
                 Text(
                   '$_counter',
                   style: TextStyle(fontSize: 48, fontWeight: FontWeight.bold),
                 ),
                 SizedBox(height: 20),
                 ElevatedButton(
                   onPressed: _incrementCounter,
                   child: Text('Increment Counter'),
                 ),
               ],
             ),
           ),
         ),
       );
     }
   }

This code defines a simple Flutter app with a counter that increments when a button is pressed.

Step 4: Running the App

You can run your Flutter app on an emulator or a physical device:

1. Ensure you have an emulator or a physical device connected and recognized by Flutter.

2. Run the following command to start the app:
   

   flutter run

This command will build and run the app on the selected device.

Conclusion

Congratulations! You've successfully created a basic Flutter app. Flutter's extensive widget library and cross-platform capabilities make it a powerful choice for developing mobile applications. You can expand on this tutorial by exploring more Flutter widgets, adding navigation, integrating APIs, and building more complex and feature-rich apps. Happy coding!