Flutter is a mobile app SDK that allows you to create high-quality native apps on iOS and Android. It is also the primary way to develop cross-platform apps with Google's new Fuchsia operating system. The Flutter framework makes it easy for you to build user interfaces that are beautiful, fast, and responsive. The framework is also extensible, so you can easily add new features and functionality. When creating a Flutter app, you'll be working with what's called a "widget." Widgets are the basic building blocks of a Flutter app, and they're used to create both the visual components of an app (like buttons and text) and the functional elements (like Stateless Widgets).

There are two types of widgets: Stateless Widgets and Stateful Widgets. As the name suggests, Stateless Widgets are those with no internal state (or "state," for short). These are the most straightforward widgets and are often used for buttons or text. On the other hand, Stateful Widgets have an internal state, and this state can be changed over time, and it will be reflected in how the widget looks and behaves. Stateful Widgets are often used for user input fields or animation controllers. You can easily create both Stateless and Stateful Widgets using the Dart programming language. You can also use various other development tools to help with the development process, including the Dart Analyzer and the Flutter Inspector.