Dart is an application programming language that’s easy to learn, easy to scale, and deployable everywhere. Google depends on Dart to make very large apps.
NB: If you've jumped on the ES6 and Beyond train, then much of the syntax of Dart will look awfully familiar.
Dart is currently in production at Google Fiber and Goodgle Ads Team (to name a few).
There's a nifty tool that's similar to JSFiddle or CodePen, but for Dart called DartPad.
Theres also a special browser called Chromium, made at Google, that runs native Dart code. So it's a bit faster to use with Dart.
Pub -- the package manager similar to npm.