This repository is a complete mirror of the World of Warcraft game client's UI source code, provided by Blizzard for reference by addon developers. It contains hundreds of official Blizzard addons written in Lua and XML, covering every in-game interface element from action bars and unit frames to auction house, map, and housing systems. The architecture is heavily event-driven and based on a mixin composition pattern (CreateFromMixins), with extensive use of frame pools, data providers, and secure/taint-aware coding. The codebase is production-grade and actively maintained alongside the game's releases, making it the authoritative reference for WoW addon development. While nearly all components are tightly coupled to WoW's proprietary APIs, several isolated utility libraries (color math, vector math, bit flags, export/import streams) demonstrate patterns that could be extracted for general Lua projects.