What does CSS stand for?

CSS stands for Cascading Style Sheets. This terminology is fundamental in web design and development, as CSS is a stylesheet language used to describe the presentation of a document written in HTML or XML. It allows developers to control the layout, colors, fonts, and overall style of web pages, enabling the separation of content and design.

In the context of web development, "cascading" refers to the way styles can be applied to elements through various sources, such as inline styles, internal stylesheets, and external stylesheets. This layering of styles is what gives CSS its power and flexibility in designing responsive, visually appealing websites.

The other terms provided in the choices do not accurately depict the function or definition of CSS in web design. Therefore, understanding that CSS stands for Cascading Style Sheets is crucial for anyone learning about front-end development.