This reference implementation of PatternFly is based on [Bootstrap v3](http://getbootstrap.com/). Think of PatternFly as a "skinned" version of Bootstrap with additional components and customizations.
Packs ECMAScript/CommonJs/AMD modules for the browser. Allows you to split your codebase into multiple bundles, which can be loaded on demand. Supports loaders to preprocess files, i.e. json, jsx, es7, css, less, ... and your custom stuff.