SCSS (Sassy CSS) is a preprocessor for CSS that adds programming features to stylesheets, such as variables, nesting, and functions. It allows developers to write cleaner and more maintainable styles by organizing code into modular components. SCSS compiles into standard CSS, ensuring compatibility with all browsers. It supports reusable mixins, making it easier to manage consistent styling across projects. SCSS is widely used in web development to streamline and enhance styling workflows.