SASS/SCSS is an improvement of CSS; it's translated into normal CSS before being sent to users.
The original SASS program, written in Ruby, compiles two syntaxes: SASS (indented syntax) and SCSS (a superset of normal CSS).
There is now a C/C++ implementation of SASS/SCSS called libsass. You can get a C version of the compiler frontend, or use it through a Node.js wrapper (e.g. gulp-sass, grunt-sass). pyScss is a compatible compiler in Python, which only compiles SCSS; there are also Python bindings for libsass.
See also Compass.
Some interface builders are being created for it to help get started quickly: