CSS, what it is, and some great examples.

CSS - Short for Cascading Style Sheets, a feature added to HTML developed by the W3C, that gives both web site developers and users more control over how pages are displayed. With CSS, designers and users can create style sheets that define how different elements, such as headers and links, appear. These style sheets can then be applied to any web page.

A great example of how CSS can be applied to change a website is the CSS Zen Garden.

If you want to dabble with CSS yourself, another great starting point is The Layout Reservoir.