HTML is a standard defined by the WHATWG, an organization formed by people working on the most popular web browser. Previously W3C (World Wide Web Consortium) was the organization in charge of creating the HTML standard.
During early 2000, people believed that XML was the future of web, so HTML moved from being an SGML-based authoring language to an XML markup language.
Eventually browser vendors realized this was not the right path for the Web, and they pushed back, creating what is now known as HTML5.
W3C did not really agree on giving up control of HTML, and for years we had 2 competing standards, each one aiming to be the official one. Eventually on 28 May 2019 it was made official by W3C that the "true" HTML version was the one published by WHATWG.
The HTML's childhood:
HTML5 is not just HTML anymore. It is a term that now defines a whole set of technologies, which includes HTML but adds a lot of APIs and standards like WebGL, SVG and more.
There is no such thing (any more) as an HTML version now. It's a living standard.
Like CSS, which is called "3", but in reality is a bunch of independent modules developed separately.
Like JavaScript, where we have one new edition each year, but nowadays, the only thing that matters is which individual features are implemented by the engine.
HTML is the markup language we use to structure content that we consume on the Web.
It's success is based on one thing: simplicity. It resisted being hijacked into an XML dialect via XHTML.
Another feature it provides us is forgiveness. There are some rules, right, but after you learn those, you have a lot of freedom. Browsers learned to be resilient and to always try to do their best when parsing and presenting HTML to the users. Browsers learned to be resilient and to always try to do their best when parsing and presenting HTML to the users.