Syntactically Awesome Style Sheets (Sass) is a preprocessor scripting language that is interpreted or compiled into Cascading Style Sheets (CSS). It exists in two syntaxes: the original indented syntax (.sass), which uses whitespace for structure, and the more popular SCSS (.scss), which uses CSS-like braces and semicolons.
Since browsers cannot interpret Sass directly, the code must be compiled into standard CSS using the appropriate tools.