Flutter, developed by Google in 2017, is a popular open-source UI toolkit for creating cross-platform applications from a single codebase using the Dart programming language. It has gained significant traction among developers due to its expressive UI, high performance, and ongoing community growth, with over 2 million developers and 90,000 apps published. The latest version, Flutter 2.2, enhances app monetization and functionality, positioning it as a leading framework for mobile app development.