ECMAScript 6 is the upcoming version of the ECMAScript standard. This standard is targeting ratification in June 2015. ES6 is a significant update to the language, and the first update to the language since ES5 was standardized in 2009. Implementation of these features in major JavaScript engines is underway now.
Babel will turn your ES6+ code into ES5 friendly code, so you can start using it right now without waiting for browser support.