Flutter is an open-source, cross-platform UI toolkit created by Google. It is used to create native-looking applications for mobile, web, and desktop. Flutter is a relatively new language, but it has quickly gained popularity due to its speed, performance, and ease of use.

Flutter apps are written in the Dart programming language. Dart is a compiled language, meaning the code is converted into machine code before it is executed. This makes Flutter apps faster than interpreted languages, such as JavaScript.