Babel.js: what is it?
Babel transpiles your ES6 code back down to older, more compatible ES5 syntax for browser back-compatibility. Javascript is famously an interpreted language, and doesn’t require compiling to run in your browser, however, Javascript has suffered (thrived under?) a climate of confusingly named competing version and specs since its inception.
From Livescript to Jscript to ECMAScript to ES2015 to ES6,
Babel lets you write Javascript in the dialect of your choice, and then “transpile” (translate / compile) your code into a “pile” of similar but different JS that works in today’s browsers (or yesterday’s browsers, or tomorrow’s browsers). – Jared Leto