1. Short for Cascading Style Sheet, CSS is a concept first created by Håkon Wium Lie in 1994. In December 1996, CSS was made a specification by the W3C and today allows web developers to alter the layout and appearance of their web pages. For example, CSS may be used to change the font used in certain HTML element, as well as its size and color. A single CSS file may be linked to multiple pages, which allows a developer to change the appearance of all the pages at the same time.

The following box contains a basic example of using CSS code to define fonts, the color of hyperlinks, and the color of a link when the mouse cursor hovers over it. In this specific example, we are only changing the HTML tags <a> and <body>, rather than creating any new class or id selectors.

body {
  font: normal 100% "trebuchet ms", Arial, Helvetica, sans-serif;
a {
  color: #000000;
A:visited {
  color: #005177;
a:hover {
  color: #005177;

The CSS code in the box above can be inserted into the head section of a page's HTML using the following code. However, keep in mind that performing this action only applies these changes to a single page.

<style type="text/css">
     above code inserted here

If you want to use the CSS code on multiple pages, we suggest storing the code in a separate CSS file and then loading it on every page. For example, the CSS code shown in the first box on this page can be copied and pasted into a file with the .css file extension.

Tip: A CSS file can be created using any text editor or even Notepad if you're using Windows.

After the file has been saved, it must linked to in the head of the HTML code using the <link> tag. The following box shows an example of this element in use.

<link rel="stylesheet" Type="text/css" href="URL or path to css file here">

If you named the file example.css (and it was in the same directory as the HTML file it is being loaded for), the following would link it.

<link rel="stylesheet" Type="text/css" href="example.css">

CSS3 is the version of CSS (Cascading Style Sheets) that replaces CSS2. It introduces a number of new selectors and properties that allow for more flexibility with page layout and presentation. Some updates, such as the box-shadow property (which allows a drop-shadow to be added to an element), allow visual effects to be applied without the need for creating special images.

Related pages

2. Short for Content Scramble System, CSS is a protection scheme used to help protect copyrighted material stored on DVDs from being copied.

Also see: <head>, Class, Cross-site scripting, Div, DRM, Programming terms, Sprite, Style, Stylesheet, Web design, XSL