CSS stands for Cascading Style Sheets, and a style is a rule describing how your webpage should be displayed. Infact, it’s a set of rules that are applied to all the content on your website.

CSS style rules can be mixed with the HTML code or ‘tags’ or they can be collated in a separate ’style sheet’ and applied to all of the webpages on your site. Using a separate style sheet separates the content from it’s presentation.

Before CSS was created, web page designers mixed the presentation, such as colours, fontstyles, sizes, position on the screen, with the headings, text, images and logos. This made for large, clunky pages of code.

Using CSS is the modern way of designing websites and although the rules appear cryptic, strange and very different from HTML, there are many benefits to building sites this way,

• CSS offers far more, and more powerful formatting or presentation choices, for example, you can control the space between paragraphs (called leading)
• CSS takes up much less space on your webpages so they are uncluttered, easier to build and load faster in the users browser
• Many of the HTML formatting tags are discontinued in the W3C (World Wide Web Consortium) new standards for XHTML - standards that designers use.
• CSS makes updating your site much easier. Instead of changing, say, all your h2 headings to Verdana, 16 points, blue, on every page, you just change the style sheet and it changes all your pages.
• The search engine spiders will love your cleaner, faster loading pages and will rank them better because the content with the important keywords will not drown in a sea of formatting code.

Unfortunately, CSS did not come with a good manual, however, David Sawyer McFarland has written an excellent guide called CSS - The missing manual, available online or from bookstores.