HTML CSS and JavaScript: Each Layer's Job
Understand what HTML, CSS, and JavaScript each contribute to a webpage and why separating concerns makes sites maintainable.
The Three Pillars of the Web
Every webpage is built from three complementary technologies: HTML for structure, CSS for presentation, and JavaScript for behaviour. Keeping them separate is one of the most important principles in frontend development.
HTML — Structure and Meaning
HTML (HyperText Markup Language) describes what content is. A heading, a paragraph, a list, a form — HTML gives content semantic meaning that browsers, search engines, and screen readers all understand.
<!DOCTYPE html>
<html lang="en">
<head><title>My Page</title></head>
<body>
<h1>Hello World</h1>
<p>This is a paragraph.</p>
</body>
</html>All lessons in this course
- Browsers DNS and HTTP: The Request Lifecycle
- HTML CSS and JavaScript: Each Layer's Job
- How a Page Renders: Parsing DOM CSSOM Layout Paint
- Developer Tools: Opening and Using DevTools