SCSS (Sassy CSS) is a preprocessor scripting language that is compiled or interpreted into Cascading Style Sheets (CSS). SCSS is an extension of CSS, adding features like variables, nesting, mixins, functions, and more. These features allow developers to write more modular, maintainable, and efficient CSS code. SCSS files are not directly interpreted by web browsers; instead, they must be processed by an SCSS compiler (such as the Sass gem or Node Sass) to generate standard CSS files. This compilation step enables developers to use the advanced features of SCSS during development while ensuring that the final output is compatible with all web browsers. SCSS promotes code reusability and organization, making it a popular choice for large-scale web projects and front-end frameworks.