Sass, Syntactically Awesome Stylesheets
Sass is a stylesheet language initially designed by Hampton Catlin and developed by Nathan Weizenbaum. It is best described as a meta-language on top of CSS, and is meant to abstract CSS code and create simpler stylesheet files.
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. Sass both provides a simpler, more elegant syntax for CSS and implements various features that are useful for creating manageable stylesheets.
Note that Sass is written in Ruby, so you’ll need Ruby installed as well. If you’re using OS X, it’s already there. Windows users can get it via the Ruby Installer for Windows. Linux users click here.
Font: Wikipedia SASS