Sass is a meta-language on top of CSS that’s used to describe the style of a document cleanly and structurally, with more power than flat CSS allows.

The Compass system is an open-source and uses Sass to help with worflow and organises stylesheets Compass/Sass framework offers the ability to add variables, mixins, and nesting whilst writing CSS.

Implementing thse into projects allows a more flexible workflow and also smaller and your web site easier to maintain. It’s CSS with intelligence!

Video below gives an introduction to Compass from Lorin Tackett on Vimeo.

And you can test Sass directly online! (Sass and Compass are installed through RubyGems and run on the command line)