According to its overview:
Dart addresses issues with traditional web development languages while remaining easy to learn. Thanks to optional static types, Dart scales from simple scripts to large apps.
The highlights of the new release of the Dart SDK include:
A faster Dart Virtual Machine that claims to outperform V8 on some Octane tests.
An HTML library that works transparently on modern browsers.
A new package manager, Pub
A server-side I/O library.
The SDK comes with a language specification describing Dart semantics, including many features new in this release.
It also includes the browser Dartium, the Chromium build with native Dart support. that we originally saw as an experimental release in February and a standalone lightweight editor to help developers refactor and debug code which is introduced in the video below. You can also use Eclipse, IntelliJ and Webstorm which have Dart plugins.
To know more about Dart, see Seth Ladd's 4-minute video, Introducing Dart: