YUI 3 — Yahoo! User Interface Library

YUI 3 — Yahoo! User Interface Library: "YUI 3 is Yahoo!'s next-generation JavaScript and CSS library. It powers the new Yahoo! homepage and incorporates what we've learned in five years of dedicated library development. As of the 3.1.1 release, the YUI 3 Library has grown to include the core components, a full suite of utilities, the Widget Infrastructure, and a few Widgets. All YUI projects are BSD-licensed and are available for forking and contribution on GitHub."