In September 2009, Yahoo! released YUI 3, a new version of YUI rebuilt from the ground up to modernize the library and incorporate lessons learned from YUI 2. Among the enhancements are a CSS selector driven engine, like jQuery, for retrieving DOM elements, a greater emphasis on granularity of modules, a smaller seed file that loads other modules when necessary, and a variety of syntactic changes intended to make writing code faster and easier.
The YUI Library project at Yahoo! was founded by Thomas Sha and sponsored internally by Yahoo! co-founder Jerry Yang; its principal architects have been Sha, Adam Moore, and Matt Sweeney. The library’s developers maintain the YUIBlog; the YUI community discusses the library and implementations in its community forum.