This content originally appeared on DEV Community and was authored by Karthikeyan
Hello, history buffs and markup masters! 
We’ve unlocked advanced attributes in Part 18 of our The Power of HTML series. Now, in Part 19, we’re time-traveling through HTML’s evolution—from the rigid days of XHTML to the dynamic HTML Living Standard. As of July 20, 2025, HTML continues to adapt, powering everything from simple sites to AI-driven apps. Understanding this history helps you appreciate why semantics (Part 2) and APIs (Part 6) matter today.
HTML’s journey reflects the web’s growth: from static docs to interactive experiences. We’ll cover key milestones, changes, and how AI tools like ChatGPT (handy for summarizing timelines) or Grok (excellent for generating code comparisons from different eras) can help explore it. Prompt example: “Compare HTML4 and HTML5 code for a simple form.” Let’s rewind and evolve!
The Roots: Early HTML to HTML 4.01
HTML started in 1991 with Tim Berners-Lee’s basic tags for linking documents. By 1999, HTML 4.01 became the standard, introducing better structure, styles via CSS, and accessibility features like alt attributes. It was versioned, with strict rules, but the web craved more—multimedia, apps, and cleaner code.
This era’s HTML was declarative, focusing on content over presentation (which CSS handled).
The Rise of XHTML: XML Meets HTML
In the early 2000s, XHTML reformulated HTML 4.01 as XML—stricter syntax, self-closing tags (e.g., <br />), and lowercase elements.XHTML 1.0 (2000) added no new features but enforced well-formedness, aiding parsers and tools.
XHTML2 aimed for modularity but stalled—too rigid, ignoring browser realities. Developers wanted evolution, not revolution.
AI insight: Ask ChatGPT or Grok: “Generate XHTML vs HTML5 example for the same page layout.”
The Split: WHATWG and the Birth of HTML5
Frustrated with W3C’s XHTML focus, browser vendors formed WHATWG in 2004 to create a “living standard”—always evolving, no versions. This led to HTML5 (finalized 2014), adding <video>, <canvas>, semantics (<article>, <nav>), and APIs (geolocation, storage—Part 6).
HTML5 bridged old and new, supporting error-handling for real-world code. W3C and WHATWG clashed on approaches—snapshots vs. flux—but reconciled in 2019, unifying under the HTML Living Standard.
The HTML Living Standard: Continuous Evolution
Today, HTML is a “living standard” at html.spec.whatwg.org—no more versions like HTML 5.3 (a misconception; it’s iterative). Updates happen via proposals, browser implementations, and community input. Recent changes (as of 2025) include better accessibility (e.g., enhanced ARIA integration), performance hints (like loading="lazy"), and support for emerging tech like Web Components (Part 8).
This model keeps HTML relevant—adapting to AI-generated content or PWAs without breaking backward compatibility.
Example Evolution: Old XHTML form vs. Modern HTML.
XHTML (strict):
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head><title>Form</title></head>
<body>
<form action="/" method="post">
<input type="text" name="name" />
</form>
</body>
</html>
Modern HTML Living Standard:
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Form</title>
</head>
<body>
<form action="/" method="post">
<input type="text" name="name" required>
</form>
</body>
</html>
See the simplicity? Added attributes like required for native validation.
AI Tools for Exploring HTML History
- ChatGPT: “Summarize HTML evolution timeline.”
- Grok: “Compare code samples from XHTML to HTML5 for multimedia embedding.”
These help visualize changes—great for learning or migrating old code.
Key Takeaways and Preview
- HTML evolved from versioned specs (HTML4, XHTML) to a flexible living standard, emphasizing practicality and innovation.
- Recent focuses: Accessibility, performance, and integration with web tech.
- Next: Part 20 — AI-Generated HTML: Tools and Best Practices!
Like, share your HTML history facts, and follow! 
This content originally appeared on DEV Community and was authored by Karthikeyan