What is HTML? The language every web page is written in

HTML, short for HyperText Markup Language, is the language web pages are written in. It is plain text with labels called tags that tell a browser what each part of the page is: this is a heading, this is a paragraph, this is a link, this is an image. The browser reads those labels, builds the page's structure, and draws it. HTML says what things are; how they look and behave is left to other languages.

In short

• HTML marks up text with tags, such as a heading tag or a link tag, so a browser knows what each piece of a page is.
• A browser turns HTML into a tree of elements, then styles it with CSS and lets JavaScript change it.
• HTML is a markup language, not a programming language, and today it is one "living standard" that browser makers update continuously.

How does HTML work?

An HTML file is ordinary text. Inside it, tags wrap pieces of content. A tag is a name in angle brackets, and most come in pairs, an opening tag and a closing tag with a slash, with the content between them. Together the tags and content make an element. Some tags carry attributes, extra information written inside the opening tag, such as the web address a link points to.

The tags describe meaning, not appearance. A top-level heading tag says "this is the main heading," not "this is big and bold." The browser has default styles, so headings do look big, but the point of the markup is that a browser, a search engine and a screen reader for blind users can all tell what each part is.

What does a simple web page look like?

Here is a complete, valid page, twelve lines long:

<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <title>My first page</title>
</head>
<body>
  <h1>Hello, web</h1>
  <p>This is a paragraph with <a href="https://example.com">a link</a>.</p>
  <img src="cat.jpg" alt="A ginger cat asleep on a chair">
</body>
</html>

Going through it line by line, with what the browser does at each step:

1. The doctype tells the browser this is modern HTML, so it uses the standard rules rather than an old compatibility mode.
2. The html element wraps the whole page; its lang attribute says the page is in English, which helps screen readers pronounce it and translation tools offer help.
3. The head holds information about the page that isn't shown in the page itself.
4. The meta charset line says the text is encoded as UTF-8, so letters such as é or 字 display correctly.
5. The title is the text shown in the browser tab, and search engines often use it as the headline of a search result. It does not appear on the page.
6. The head closes.
7. The body opens. Everything inside it is the visible page.
8. The h1 is the main heading. The browser shows it large and bold by default, and search engines and screen readers treat it as the page's headline.
9. The p is a paragraph, and the a inside it is a link, an "anchor"; its href attribute is the address it leads to. This one tag is the hypertext in HyperText Markup Language.
10. The img places an image. Its src names the file, which the browser fetches with a separate request. Its alt text describes the image for people who can't see it, and appears if the file fails to load. It has no closing tag, because it holds no text.
11. The body closes.
12. The html element closes, and the page is complete.

That is the whole skeleton of every web page, from a student's homepage to a news site. Big sites have thousands of elements, but they are made of the same parts.

What does a browser do with HTML?

A browser turns the text into a page in a few steps, as MDN's guide to how browsers work describes. First it downloads the file over the internet, using HTTP, the protocol explained in how the internet works. Then it parses the HTML: it reads the tags in order and builds a tree in memory called the Document Object Model, or DOM, with html at the root, head and body as branches, and every heading, paragraph and link as a leaf. Whenever it meets an image, stylesheet or script, it starts fetching those too.

Next it works out each element's style from CSS, calculates where every box goes on the screen, and paints the pixels. If JavaScript on the page changes the DOM, adding a message or hiding a menu, the browser redraws the parts that changed.

Browsers are forgiving. If a closing tag is missing or tags overlap, the browser doesn't stop with an error. The HTML standard spells out exactly how to repair each kind of mistake, so the same broken page comes out the same in every browser. That tolerance is one reason the web grew so fast: anyone could write a page, and small errors didn't break it.

How are HTML, CSS and JavaScript different?

Most web pages use three languages together, each with its own job.

	HTML	CSS	JavaScript
Its job	Structure and meaning	Appearance and layout	Behavior
It answers	What is this part?	How should it look?	What should happen when…?
Example	This is a heading, that is a link	Headings are dark blue; the menu sits on the left	When the button is clicked, show the next photo
Kind of language	Markup	Style sheet	Programming language
Can the page work without it?	No	Yes, plain but readable	Usually, for simple pages

The split is deliberate. The same HTML can be restyled completely by changing only its CSS, and a page whose structure is sound in HTML still works when a script fails to load.

Is HTML a programming language?

No. A programming language, such as JavaScript or Python, has variables, conditions and loops: it can calculate, decide and repeat. HTML can do none of that. It describes a document, much as headings and bold type describe a printed page. That doesn't make it trivial. Choosing the right element, a real button rather than a clickable box, a heading rather than large text, is what makes a page usable with a keyboard or a screen reader, and helps search engines understand what a page is about.

Where did HTML come from, and who decides what's in it?

The British scientist Tim Berners-Lee invented HTML at CERN, the European physics laboratory, as one of the three pieces of the World Wide Web alongside web addresses and HTTP; the story of that invention is in the difference between the internet and the web. His early list, HTML Tags, described a small set: a title, headings, paragraphs, lists and the anchor for links. Images came later, added by browser makers.

Year	Milestone
1991–92	Berners-Lee's first tags, published on the first web server
1995	HTML 2.0, the first formal standard, published by the IETF as RFC 1866
1997	HTML 3.2 and then HTML 4.0 from the World Wide Web Consortium (W3C)
1999	HTML 4.01, the version most of the early-2000s web was written in
2004	Apple, Mozilla and Opera form the WHATWG to develop HTML for web applications
2014	The W3C publishes HTML5 as a finished standard, in October
2019	The W3C and WHATWG agree on 28 May to work on one HTML standard, the WHATWG's

Since then there has been one HTML standard, with no version numbers. The HTML Living Standard is updated continuously, and features are added when browser makers agree to build them. "HTML5" survives as a name for modern HTML in general.

Check yourself

• Without looking back, explain why an HTML heading tag describes meaning rather than appearance.
• What does a browser build from HTML before it draws anything on the screen?
• Give one job each for HTML, CSS and JavaScript on the same page.

Sources

• HTML Living Standard — WHATWG, 2026
• HTML Tags — Tim Berners-Lee, W3C archive, 1992
• RFC 1866: Hypertext Markup Language 2.0 — Internet Engineering Task Force, 1995
• Memorandum of Understanding Between W3C and WHATWG — World Wide Web Consortium, 2019
• Populating the page: how browsers work — MDN Web Docs, Mozilla, 2026