SASS is a stylesheet language not unlike CSS - in fact, it compiles to CSS. But it adds programmatic logic, element nesting, mixins and variables. This means that CSS can be written with less repetition through the sharing of styling rules, so when it comes time to rewrite, edit or refactor the developer isn’t sifting through hundreds of lines of code looking for every incidence of a rule. Instead, they just change a variable. There’s a reason the A stands for Awesome!