How HTML Works

HTML is the foundation of every web page. It tells a web browser what different pieces of content are and how they are structured.

When you visit a website, your browser receives and processes HTML along with other resources such as CSS, JavaScript, images, and fonts. The browser then turns that information into the web page you see on your screen.

Understanding how HTML works helps you understand what happens between writing HTML code and viewing a website.

How HTML Works

The basic process can be understood like this:

HTML File
    ↓
Browser Reads HTML
    ↓
HTML Is Parsed
    ↓
DOM Is Created
    ↓
CSS and Other Resources Are Processed
    ↓
Browser Renders the Page
    ↓
Web Page Appears

For example, consider this HTML:

<!DOCTYPE html>
<html>

<body>

    <h1>Welcome to HTML</h1>

    <p>This is my first web page.</p>

</body>

</html>

The browser reads the HTML and identifies the different elements.

It understands that <h1> represents a heading and <p> represents a paragraph. It then uses this information to display the content on the page.

HTML Provides Structure

HTML describes the structure and meaning of content.

For example:

<h1>Learn HTML</h1>

<p>
    HTML is used to structure web pages.
</p>

The browser understands that Learn HTML is a heading and the second piece of content is a paragraph.

HTML is therefore more than simply writing text. It gives content a meaningful structure.

HTML Uses Elements

HTML is made up of elements.

For example:

<p>Hello World</p>

This is a paragraph element.

It contains an opening tag:

<p>

the content:

Hello World

and the closing tag:

</p>

Together, they form the complete HTML element.

Different elements represent different types of content.

<h1>Main Heading</h1>

<p>A paragraph.</p>

<a href="about.html">About Us</a>

<img src="photo.jpg" alt="Example photo">

Each element tells the browser something different about the content.

HTML Attributes

HTML elements can also contain attributes.

For example:

<a href="https://example.com">
    Visit Example
</a>

Here, href is an attribute. It tells the browser where the link should take the user.

An image can also have attributes:

<img
    src="laptop.jpg"
    alt="Laptop displaying code"
>

Here:

Attribute	Purpose
src	Specifies the image location
alt	Describes the image

Attributes provide additional information about an HTML element.

The Browser Parses HTML

When a browser receives an HTML document, it parses the document.

Parsing means that the browser reads the HTML and identifies its elements, attributes, text, and relationships.

For example:

<body>

    <h1>HTML Tutorial</h1>

    <p>Learn HTML step by step.</p>

</body>

The browser can understand the structure conceptually as:

BODY
├── H1
│   └── HTML Tutorial
│
└── P
    └── Learn HTML step by step.

This structure is used by the browser when displaying the page.

What Is the DOM?

DOM stands for Document Object Model.

The DOM is a structured representation of an HTML document.

For example:

<h1>Welcome</h1>

<p>Hello World</p>

can be represented as:

Document
├── H1
│   └── Welcome
│
└── P
    └── Hello World

The DOM also allows JavaScript to access and change HTML elements.

For example:

const heading = document.querySelector("h1");

heading.textContent = "Hello HTML";

JavaScript finds the <h1> element and changes its content.

HTML Works With CSS

HTML provides structure, while CSS controls presentation.

HTML:

<h1>Learn HTML</h1>

CSS:

h1 {
    color: blue;
    font-size: 40px;
}

The HTML tells the browser that the content is a heading.

The CSS tells the browser how that heading should look.

This separation allows developers to change the design without changing the underlying content structure.

Note: HTML describes content and structure. CSS is normally used for styling and layout.

HTML Works With JavaScript

JavaScript adds behavior and interaction to HTML pages.

For example:

<button id="myButton">
    Click Me
</button>

JavaScript can make the button interactive:

const button = document.getElementById("myButton");

button.addEventListener("click", function () {
    alert("Hello from JavaScript!");
});

In this example, HTML creates the button and JavaScript responds when the user clicks it.

How HTML Loads Other Resources

An HTML page can reference external files.

For example:

<link rel="stylesheet" href="style.css">

loads a CSS file.

JavaScript can be loaded using:

<script src="script.js" defer></script>

Images can be referenced using:

<img src="photo.jpg" alt="A landscape">

The browser requests these resources and uses them while processing the page.

A typical web page may therefore contain:

HTML
 ├── CSS
 ├── JavaScript
 ├── Images
 ├── Fonts
 └── Other Resources

How HTML Creates a Complete Page

Consider this example:

<!DOCTYPE html>
<html lang="en">

<head>

    <meta charset="UTF-8">

    <meta
        name="viewport"
        content="width=device-width, initial-scale=1.0"
    >

    <title>HTML Tutorial</title>

</head>

<body>

    <header>
        <h1>How HTML Works</h1>
    </header>

    <main>

        <p>
            HTML provides the structure of a web page.
        </p>

        <a href="about.html">
            Learn More
        </a>

    </main>

</body>

</html>

The browser processes the document and identifies the different elements.

It understands the document structure, creates the DOM, loads referenced resources, and renders the final page.

HTML Rendering Process

A simplified view of the browser process is:

HTML Source
     ↓
HTML Parsing
     ↓
DOM
     ↓
CSS Processing
     ↓
Layout
     ↓
Rendering
     ↓
Web Page

The actual browser process is more complex, but this model is enough to understand the basic idea.

HTML provides the information the browser needs to understand the document.

Frequently Asked Questions

How does HTML work?

HTML works by describing the structure and meaning of content in a web document. The browser parses the HTML, creates a DOM, processes related resources, and renders the page.

What happens when a browser reads HTML?

The browser parses the HTML and identifies elements, attributes, text, and their relationships. It then creates a structured representation of the document.

What is the DOM?

DOM stands for Document Object Model. It is a structured representation of an HTML document that browsers and JavaScript can access and modify.

Does HTML create the design of a website?

HTML creates the structure and content. CSS is normally responsible for the visual design, styling, and layout.

Does HTML work with JavaScript?

Yes. JavaScript can access HTML elements through the DOM and change their content, attributes, styles, or behavior.

How does HTML display an image?

HTML uses the <img> element. The src attribute tells the browser where the image is located.

<img src="photo.jpg" alt="Example photo">

Why is HTML important?

HTML provides the basic structure of web pages. CSS and JavaScript build on this structure to create styled and interactive websites.

Is HTML executed like JavaScript?

No. HTML is parsed as markup by the browser, while JavaScript is executed as programming code.