Table of Contents
- What is the Web?
- How the Web Works
- Understanding HTML: The Foundation of Web Pages
- What is the DOM?
- How HTML and the DOM Interact
- Key Terminology to Know
- Why Learn HTML and the DOM?
- Conclusion
1. What is the Web?
The World Wide Web, often referred to simply as “the web,” is a vast system of interlinked hypertext documents accessed through the internet. When you type a URL into your browser, you’re essentially requesting a specific document stored on a remote server somewhere around the world. This document, most often an HTML file, is interpreted and rendered by the browser to display a visually structured page.
The web is built upon three fundamental technologies:
- HTML (HyperText Markup Language): The backbone of any webpage, defining structure and content.
- CSS (Cascading Style Sheets): The styling language that controls how elements look.
- JavaScript: The scripting language that adds interactivity and dynamic behaviors.
Before diving into HTML and CSS, it’s crucial to understand the web’s foundational workflow and how everything ties together.
2. How the Web Works
When you visit a website, here’s what typically happens:
- DNS Resolution: Your browser resolves the domain name (like
example.com) to an IP address using the Domain Name System (DNS). - HTTP Request: The browser sends an HTTP request to the server at that IP address.
- Server Response: The server returns the requested HTML document.
- Rendering: The browser reads the HTML and may subsequently request additional assets like CSS, JavaScript, and images.
- Final Output: The browser constructs the page in memory using a representation called the DOM, then renders it visually.
This workflow might involve many more details (like caching, redirects, cookies, etc.), but at its core, the process is designed to request and render documents over the internet using standard protocols.
3. Understanding HTML: The Foundation of Web Pages
HTML (HyperText Markup Language) is the standard markup language used to create web pages. It describes the structure of a webpage using elements (also called tags), which browsers interpret to render content.
An HTML document consists of nested elements such as:
<!DOCTYPE html>
<html>
<head>
<title>My First Webpage</title>
</head>
<body>
<h1>Hello, world!</h1>
<p>This is my first web page using HTML.</p>
</body>
</html>
Each element has a specific role. For example:
<html>wraps the entire document.<head>contains meta-information like the page title.<body>includes all visible content.<h1>is a top-level heading.<p>is a paragraph of text.
HTML is not a programming language—it’s a markup language, meaning it annotates content so that browsers can render it correctly.
4. What is the DOM?
The Document Object Model (DOM) is a tree-like representation of an HTML document in memory. As the browser reads the HTML, it constructs a corresponding DOM, where each element becomes a node in a tree structure.
For example, the earlier HTML snippet would be represented in the DOM as a tree where:
- The root node is the
<html>tag. - It has two children:
<head>and<body>. <body>contains<h1>and<p>nodes.
The DOM is crucial because it’s what browsers interact with when rendering and modifying the page. JavaScript manipulates the DOM to create dynamic content, respond to user actions, and much more.
5. How HTML and the DOM Interact
While HTML defines the initial structure of a web page, the DOM is what browsers use internally. You can think of HTML as the source code and the DOM as the in-memory model created by interpreting that source.
This distinction becomes important when you start working with JavaScript. JavaScript doesn’t modify the HTML file itself—it modifies the DOM. And those changes are immediately reflected in the browser.
For instance, if JavaScript changes a <p> tag’s content, the original HTML file doesn’t change. But the DOM is updated, and the browser shows the new content.
6. Key Terminology to Know
Before moving ahead, it’s important to get comfortable with some foundational terms:
- Markup: Annotations added to content using tags.
- Element: A basic building block in HTML (e.g.,
<div>,<h1>). - Attribute: Additional information provided to elements (e.g.,
class,id,src). - Tag: The syntax used to define elements, such as
<a>,<img>. - Node: A unit in the DOM tree, can be an element, text, or comment.
- Render: The process of displaying content based on the DOM and CSS.
7. Why Learn HTML and the DOM?
Whether you’re pursuing front-end development, full-stack development, or even digital marketing and SEO, understanding HTML and the DOM is essential. Here’s why:
- Every web page is built with HTML: It’s the universal foundation of the web.
- Accessibility and SEO depend on proper HTML structure: Search engines and screen readers rely on semantic HTML.
- DOM manipulation powers interactivity: From toggling modals to building dynamic dashboards, working with the DOM is key to user interaction.
- All major frameworks rely on these fundamentals: Even tools like React, Angular, and Vue ultimately work with the DOM.
Understanding these basics will set the stage for diving into styling (CSS), interactivity (JavaScript), and frameworks (React, Vue, etc.).
8. Conclusion
This module introduced the web’s fundamental components: HTML, the DOM, and how they tie into a browser’s rendering engine. You now understand how web pages are structured, how they’re rendered, and how the DOM acts as the dynamic interface between the browser and your code.
