Flutter is one of the newest kids in town, but one of the loudest at that. Surely the fact that Google is behind this software development kit (that we like to call framework because, at its core, that’s what it is). Flutter includes 4 major components: the Dart platform, the Flutter engine, the foundation library, and a series of design-specific widgets. 

Flutter is an open-source UI software development kit created by Google. It is used to develop cross platform applications for Android, iOS, Linux, Mac, Windows, Google Fuchsia, and the web from a single codebase.The first version of Flutter was known as codename "Sky" and ran on the Android operating system.