# HTML

Category: [Technical SEO](https://seo-geo-glossary.com/en/glossary/category/technical-seo/) › [HTML, mobile & accessibility](https://seo-geo-glossary.com/en/glossary/category/technical-seo/html-mobile-accessibility/) · Also known as: HyperText Markup Language

**HTML** (HyperText Markup Language) is the markup language that defines the meaning and structure of web content. Browsers and search engines read it to learn what a page contains. CSS describes how a page looks, and JavaScript adds behavior, according to MDN.

## How is an HTML document built?

An HTML document consists of elements. An element is usually marked by a start tag and an end tag, such as `<p>` and `</p>`, and can carry attributes that configure it. A typical page has a doctype declaration, a `<head>` with metadata such as the `<title>`, and a `<body>` with the visible content.

The HTML Standard is maintained by the WHATWG as a Living Standard, which means it is updated continuously and has no frozen version numbers. According to the WHATWG, it and the W3C signed an agreement in 2019 to collaborate on a single version of HTML. The standard also describes the in-memory representation of a page, known as the DOM.

## Why does HTML matter for SEO?

Google processes a page in three phases. It crawls the URL and parses the HTML for links, renders the page with a headless Chromium, and indexes the rendered result. Titles, headings, links and images sit in the HTML, so whatever is missing there or only appears after JavaScript runs can affect how a page is found and understood. Links count as links for Google when they are `<a>` elements with an `href` attribute.

## Example

```html
<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>Example page</title>
</head>
<body>
  <h1>Heading</h1>
  <p>A paragraph with a <a href="/page/">link</a>.</p>
</body>
</html>
```

## Common mistakes

- **Links without `href`.** According to Google, a link can generally only be crawled if it is an `<a>` element with an `href` attribute. Formats such as `<span href="…">` or `<a onclick="…">` are mostly not parsed.
- **`javascript:` addresses in `href`.** Google cannot reliably resolve these into a web address. The `href` should contain a real URL.
- **Empty link text.** Without text between the `<a>` tags there is no anchor text. For image links, Google uses the `alt` attribute, which should then not be empty.

## FAQ

**Is HTML a programming language?**
HTML is a markup language. It describes content and structure and contains no program logic.

## Related terms

- [HTML head](https://seo-geo-glossary.com/en/glossary/html-head/index.md)
- [HTML validation](https://seo-geo-glossary.com/en/glossary/html-validation/index.md)
- [Semantic HTML](https://seo-geo-glossary.com/en/glossary/semantic-html/index.md)
- [DOM](https://seo-geo-glossary.com/en/glossary/dom/index.md)
- [Raw HTML / source code](https://seo-geo-glossary.com/en/glossary/raw-html-source-code/index.md)
- [Rendered HTML](https://seo-geo-glossary.com/en/glossary/rendered-html/index.md)
- [JavaScript SEO](https://seo-geo-glossary.com/en/glossary/javascript-seo/index.md)

## Sources

- [HTML: HyperText Markup Language – MDN Web Docs](https://developer.mozilla.org/en-US/docs/Web/HTML)
- [HTML Standard, Introduction – WHATWG](https://html.spec.whatwg.org/multipage/introduction.html)
- [JavaScript SEO basics – Google Search Central](https://developers.google.com/search/docs/crawling-indexing/javascript/javascript-seo-basics)
- [Link best practices for Google – Google Search Central](https://developers.google.com/search/docs/crawling-indexing/links-crawlable)

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Last updated: October 8, 2026
URL: https://seo-geo-glossary.com/en/glossary/html/