What Is HTML and How Do Websites Work? KS3 Computing

Every webpage you visit is built using HTML — HyperText Markup Language. It is the language that tells a browser what content to display: headings, paragraphs, images, and links. Understanding HTML at KS3 gives you a clear picture of how the web is constructed, and it connects neatly to topics like networking, protocols, and cyber security.

What is HTML?

HTML stands for HyperText Markup Language. It is not a programming language (it cannot make decisions or perform calculations) — it is a markup language, meaning it describes the structure and meaning of content using tags.

The word "HyperText" refers to text that contains links to other documents — the hyperlinks that make the web a web rather than a collection of isolated pages. When Tim Berners-Lee invented the World Wide Web in 1989–1991, HTML was the language he created to express documents that could link to one another across the internet.

An HTML file is simply a plain text file saved with the .html extension. When you visit a website, your browser downloads that HTML file from a web server and renders it as a visual page.

What are HTML tags and elements?

HTML uses tags to mark up content. A tag is a keyword enclosed in angle brackets (< and >). Most tags come in pairs: an opening tag and a closing tag (which has a forward slash before the keyword):

This is a paragraph.

The opening tag , the content This is a paragraph., and the closing tag together form an element. The tag tells the browser what kind of content this is (a paragraph, p); the browser decides how to display it.

Tag | Meaning | Display effect
to | Heading levels 1–6 | Large bold text (h1) to small bold text (h6)
| Paragraph | Block of text with spacing
| Anchor (hyperlink) | Blue underlined clickable text
| Image | Displays an image
/ | Unordered / ordered list | Bullet points or numbered list
| List item | An item inside a list
| Strong emphasis | Bold
| Emphasis | Italic
| Line break | Moves to a new line (no closing tag needed)

What is the structure of a complete HTML page?

Every HTML page follows a standard structure:





My First Webpage


Welcome to Computing!
This is my first webpage. HTML is not as hard as it looks.
Visit BBC Bitesize



— tells the browser this is an HTML5 document.

— the root element; everything else goes inside it.

— contains metadata (information about the page that is not displayed directly): the title, character encoding, links to stylesheets.

— the text shown in the browser's tab.

— contains all the visible content: headings, paragraphs, images, links.

How does a browser render a webpage?

When you type a URL into your browser, the following sequence occurs:

Your browser performs a DNS lookup to find the IP address of the web server.

Your browser sends an HTTP GET request to the server.

The server responds with the HTML file.

The browser parses (reads and interprets) the HTML, building a Document Object Model (DOM) — an internal tree representation of the page's structure.

If the HTML links to CSS or image files, the browser sends additional requests to fetch those.

The browser renders the DOM to the screen, applying any CSS styles.

This entire process typically takes under a second for a well-optimised site over a fast connection.

How do CSS and JavaScript extend HTML?

HTML alone produces plain, unstyled content. CSS (Cascading Style Sheets) adds visual design — colours, fonts, layouts, and spacing. JavaScript adds interactivity — responding to button clicks, validating forms, fetching new data without reloading the page.

The three technologies have clearly separated roles:

Technology | Role | Example
HTML | Structure and content | Hello
CSS | Presentation and style | h1 { color: blue; font-size: 2em; }
JavaScript | Behaviour and interactivity | document.getElementById("btn").onclick = function() { alert("Clicked!"); }

A useful analogy: HTML is the skeleton of a building (structure), CSS is the interior design (appearance), and JavaScript is the electrical and plumbing systems (functionality).

How does HTML connect to the wider computing curriculum?

HTML is a practical bridge between several abstract KS3 topics. When you write a webpage you are:

Using a formal notation (like pseudocode, but for structure rather than logic)

Applying networking knowledge — HTTP requests, DNS, client-server architecture all play a role in delivering the page

Encountering cyber security — HTTPS secures the HTML in transit; poorly constructed web forms are a common attack vector

Practising abstraction — a tag abstracts away all the rendering decisions; you state the meaning, the browser decides the display

The DfE curriculum asks students to understand how networks facilitate communication and to use digital technologies creatively (gov.uk/government/publications/national-curriculum-in-england-computing-programmes-of-study). HTML is the most direct and visible expression of both.

Frequently asked questions

What is HTML in simple terms for KS3?

HTML (HyperText Markup Language) is the language used to describe the structure and content of a webpage. It uses tags — keywords in angle brackets — to identify different types of content: headings, paragraphs, links, images. HTML is not a programming language; it cannot perform calculations or make decisions. It tells the browser what the content is; CSS tells the browser how it should look.

What is the difference between HTML, CSS, and JavaScript?

HTML provides the structure and content of a webpage (headings, paragraphs, images, links). CSS (Cascading Style Sheets) controls how the content looks — colours, fonts, spacing, and layout. JavaScript adds interactivity — making things happen in response to user actions without reloading the page. All three work together in modern websites, but HTML alone is enough to produce a basic, working webpage.

What is a tag and what is an element in HTML?

A tag is the keyword in angle brackets that marks up content: , , . An element consists of the opening tag, the content, and the closing tag together: This is a paragraph. . Some elements (like and ) are self-closing and do not need a separate closing tag.

How does a browser know what to display when you type a URL?

When you type a URL, your browser first uses DNS to look up the IP address of the web server. It then sends an HTTP or HTTPS request to that server. The server returns an HTML file. The browser reads (parses) the HTML, sends further requests for any linked CSS, images, and scripts, and then renders the complete page on your screen. The entire process can take less than a second on a fast connection.

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