WHATWG stands for Web Hypertext Application Technology Working Group.
The group was formed as a response to the slow development of the W3C (World Wide Web Consortium) web standards in 2004 by indviduals of Apple, the Mozilla Foundation and Opera Software.
The aim of WHATWG is to evolve the web, especially HTML, by creating and extending standards and tests.
Since 2019, WHATWG is the sole publisher of the HTML and DOM standards, while their approaches on HTML standards were the "de-facto" standard for years already.
Participate in the WHATWG
Information on how to participate within the WHATWG can be found on Participation - WHATWG.
WHATWG & JokeNetwork Docs
The JokeNetwork Docs are not directly associated with the WHATWG, even though the members of JokeNetwork are also participants of the WHATWG.
The main goal of the JokeNetwork Docs is to provide documentation for the WHATWG Wiki, especially for the MetaExtensions page which you can learn more about here.
In the WHATWG WikiUp to date: v2.3.3