Yui- Yahoo! User Interface Library

YUI is a JavaScript and CSS library developed by Yahoo for building interactive web applications. It includes core functions for DOM manipulation and events, utilities for common tasks like Ajax calls and animation, UI controls like menus and sliders, and developer tools for testing and profiling applications. The document provides details on YUI's features and components. It also gives examples of how YUI can be used and lists some well-known websites that implement YUI in their designs.