whatisgithub

What is html?

whatwg/html — explained in plain English

Analysis updated 2026-06-24

★ 9,220HTMLAudience · developerComplexity · 3/5Setup · moderate

In one sentence

This repository is the source of the official HTML Standard, the living specification that defines exactly how HTML works and how browsers must parse, render, and implement every HTML feature.

Mindmap

mindmap
  root((repo))
    What it is
      HTML specification
      Living document
      Browser implementor reference
    Topics covered
      Document structure
      Element behavior
      Parsing rules
    Features specified
      Canvas drawing
      Background workers
      Server-sent events
    Contributing
      File issues
      Submit pull requests
      Build spec locally
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Code map

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filefunction / class

What do people build with it?

USE CASE 1

Look up the exact specification for how a browser must handle a specific HTML element or parsing edge case when building a browser engine or HTML tool.

USE CASE 2

File an issue or propose a fix to the official HTML Standard when you find a discrepancy between the spec and real browser behavior.

USE CASE 3

Verify how HTML features like web workers, server-sent events, or canvas are officially defined before implementing them in a browser engine.

What is it built with?

HTML

How does it compare?

whatwg/htmltikam02/devops-guidehome-assistant/home-assistant.io
Stars9,2209,2149,228
LanguageHTMLHTMLHTML
Setup difficultymoderateeasymoderate
Complexity3/51/52/5
Audiencedeveloperops devopsdeveloper

Figures from each repo's GitHub metadata at analysis time.

How do you get it running?

Difficulty · moderate Time to first run · 30min

Reading the spec requires no setup, building it locally requires following the contributing guide.

No license information was mentioned in the explanation.

So what is it?

This repository is the source for the HTML Standard, which is the official specification for the HTML language used to build web pages. HTML is the markup language that browsers interpret to display text, images, links, forms, and other content on the web. The specification defines exactly how HTML is supposed to work, covering topics like the structure of documents, how different elements behave, how browsers should parse and render HTML, and how features like storage, background workers, server-sent events, and the canvas drawing surface operate. The HTML Standard is maintained by the WHATWG, a group of browser vendors and contributors who work together to keep web standards up to date. The specification is a living document, meaning it is continuously updated rather than released in discrete versions. The actual content of the specification lives in a single large source file in this repository. The repository is a place where issues can be filed and pull requests can be submitted to propose changes or fixes to the specification. Tests that verify browser implementations match the standard are kept separately in another project called web-platform-tests. Contributors who want to preview changes locally can build the HTML output from the source file using instructions in the contributing guidelines. The README for this repository is intentionally short because the specification itself, available at the linked website, is the main document. People looking to understand HTML the language would typically read tutorials or references, not this specification, which is written for browser implementors.

Copy-paste prompts

Prompt 1
I'm building a browser engine and need to understand exactly how the HTML parser handles malformed input. Summarize the key parsing rules from the HTML Standard for recovering from missing closing tags.
Prompt 2
The HTML Standard defines how the browser event loop works. Explain the relationship between the spec's event loop model and JavaScript's call stack and task queue.
Prompt 3
I want to propose a change to the HTML Standard to add a new attribute to an existing element. Walk me through writing a well-formed pull request for the whatwg/html repository.

Frequently asked questions

What is html?

This repository is the source of the official HTML Standard, the living specification that defines exactly how HTML works and how browsers must parse, render, and implement every HTML feature.

What language is html written in?

Mainly HTML. The stack also includes HTML.

What license does html use?

No license information was mentioned in the explanation.

How hard is html to set up?

Setup difficulty is rated moderate, with roughly 30min to a first successful run.

Who is html for?

Mainly developer.

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