Flutter is a cross-platform software toolkit that enables developers to create iOS apps, Android apps, Web apps, and desktop applications with a single codebase. It is used by app makers, enterprises, and organizations around the world to rapidly develop and deploy mobile and desktop applications.

It uses the MIT-licensed Dart programming language. Dart is a flexible, modern language that makes it easier for developers to write code with speed and confidence. It has a simple syntax and strict type checking, making it familiar territory for Java and C++ programmers. It also supports code rewriting to make it faster and more maintainable.

The Flutter engine, based on the C++ library, is the backstage crew that handles all the work of drawing visuals, arranging text, managing files and network activity, supporting accessibility, allowing add-ons, and running and compiling Dart (the language Flutter apps are written in). Google developers and community members actively maintain Flutter with frequent updates, bug fixes, and improvements.

Flutter provides a rich ecosystem of packages, libraries, and tools that allow developers to extend app functionality, improve productivity, and create visually stunning apps. This thriving ecosystem is one of the key factors in the growth and success of Flutter.

Flutter apps are based on what are known as “widgets.” These widgets are small pieces of code that represent both the visual and functional aspects of an application. Widgets are composed together to achieve more complicated effects, a process called aggressive composition. The Flutter framework has a variety of widgets available that cover most common tasks, such as Boxes, States, Text, Icons, and ScrollViews.