Presentation layer

Content layer

Structure layer

Behaviour layer

.css

.html

.js

.txt

To manage user interactions

To write HTML code

To create visual styles

To store data

JavaScript

CSS

HTML

PHP

To create hyperlinks

To format text

To control actions on a web page

To display content

With a .js extension

With a .css extension

With a .txt extension

With a .html extension

To create databases

To structure the content

To manage server-side logic

To style the visual presentation

<url>

<href>

<a>

<link>

Creative Style Sheets

Computer Style Sheets

Colorful Style Sheets

Cascading Style Sheets