Flutter is an open-source UI software development kit created by Google. It's designed to help developers build natively compiled applications for mobile, web, and desktop from a single codebase. This means that with Flutter, you can write one app that runs on iOS, Android, the web, and even desktop computers.

What Flutter Does

Flutter allows developers to create beautiful, fast, and portable applications for any platform. It compiles to ARM or Intel machine code as well as JavaScript, ensuring high performance on all devices. With its hot reload feature, developers can make changes in the code and see them instantly without losing the app state, which significantly speeds up the development process.

Advantages of Flutter

1. Fast Development: Flutter's hot reload helps you quickly and easily experiment, build UIs, add features, and fix bugs.

2. Expressive and Flexible UI: Flutter's widget library allows you to create customized, beautiful, and fast apps. Plus, the ability to control every pixel ensures that the UI is expressive and flexible.

3. Native Performance: Flutter’s widgets incorporate all critical platform differences such as scrolling, navigation, icons, and fonts to provide full native performance on both iOS and Android.

Disadvantages of Flutter

1. Limited Third-Party Libraries: Flutter has a growing ecosystem, but it still lags behind more established frameworks in terms of the availability of third-party libraries.

2. Learning Curve: Developers may find Dart, the programming language used by Flutter, to have a steeper learning curve compared to other languages they might be familiar with.

3. Large App Size: Applications developed with Flutter tend to be larger than native ones, which could be a drawback for some projects.

Devices Supported by Flutter

Flutter supports a range of devices and platforms. As of the latest update, Flutter can deploy apps to iOS, Android, Windows, macOS, Linux, and web browsers. It supports mobile devices with Android SDK versions 21 to 34 and iOS devices with ARM64 architecture. For desktop, it supports macOS with x64 or ARM64 architectures and Windows with x64 or ARM64 architectures. For web deployments, it supports the latest versions of Chrome, Firefox, Safari, and Edge browsers.

In conclusion, Flutter is a powerful tool for developers looking to build cross-platform applications with a single codebase. Its advantages in speed and UI flexibility are balanced by some trade-offs in terms of app size and the learning curve for Dart. However, its growing popularity and support from Google suggest that Flutter is a strong choice for modern app development. For more detailed information about Flutter and how to get started, you can visit the official Flutter website.