The Document Object Model (DOM) is a data representation of a webpage. When your browser loads a website, it turns the HTML and CSS into a tree-like structure that you can interact with using JavaScript. Think of the DOM as the "data version" of your webpage—it represents everything you see on the screen and lets you manipulate it.

With JavaScript, you can use the DOM to change content, styles, or structure dynamically. For example, you could fetch user data and display a personalized greeting, or even build a light/dark theme toggle.

// Changing the DOM dynamically with JavaScript
document.body.style.backgroundColor = 'black';
document.body.style.color = 'white';
document.getElementById('welcome').textContent = 'Hello, Dark Mode!';

The DOM is what makes a webpage dynamic, turning static HTML into something interactive and personalized.

For a deeper dive, check out MDN Web Docs on the DOM.