Sass is a preprocessor scripting language that compiles CSS. It essentially brings the power of a standard programming language to your stylesheets. Sass files end with the `.scss` file extension.
With Sass, you can make your CSS considerably more efficient. Some of its key features include:
1.**mixins**, which allow you to apply the same style to multiple elements without having to copy and paste
2.**for**, **if**, and **else** statements, which allow you to apply styles only in specific conditions
3.**partials**, which allow you to take chunks of your CSS and import them into other `.scss` stylesheets
4.**nesting**, which allows you to order child elements inside of their parents on your stylesheet
5.**extend**, which allows you to take the style from one element into another