Technology and data formats
WHATWG
Abbreviation for Web Hypertext Application Technology Working Group
In short and in plain language
The WHATWG is a working group for the basics of the web.
It looks after the rules for the language that web pages are written in. It also sets rules for how letters are stored.
Browsers follow these rules.
Definition
The WHATWG is a working group that maintains the HTML standard and other web foundations, such as the encoding standard. Browsers follow these specifications.