Note: My goal here was to create a comprehensive list of everything you'd need in order to learn to play any class (from Level 1 to Naxxramas)—meaning I am only including class-specific resources here (so no profession guides, general leveling guides, etc). Teeb's Resource list is much broader in scope, and I highly recommend you take advantage of it (as it contains a plethora of non-class specific resources as well). If you're not aware, Teeb is also responsible for the Race & Class Comparison Tool, Dungeon Tier Sets Gallery, and a huge variety of other insanely useful resources.
Classic WoW is the highly anticipated, upcoming (re) release of the original, first World of Warcraft version, known as Classic and by it's other popular ice-cream like name: Vanilla WoW. Dubbed Retail Classic, or Official Classic by the playerbase - it was finally announced by Blizzard in November 2017, after a lot of pressure from the Private Server World of Warcraft community, since the latter's shutdown of the most popular Private Server called Nostalrius which featured the first WoW version in two separate PvP and PvE servers.