Networking & Internet

CSS

Definition

Cascading Style Sheets (CSS) is a style sheet language used for describing the presentation of a document written in a markup language such as HTML. CSS is a cornerstone technology of the World Wide Web, alongside HTML and JavaScript.

Why It Matters

CSS is what makes the web look good. It separates the presentation (style) of a web page from its content (HTML), which makes site design much more flexible and maintainable.

Contextual Example

A CSS rule like `h1 { color: blue; }` tells the browser to display all top-level headings in blue. This single rule can affect the entire website.

Common Misunderstandings

  • CSS works by selecting HTML elements and applying styles to them.
  • Frameworks like Tailwind CSS and Bootstrap provide pre-built CSS components and utilities to speed up development.

Related Terms

Last Updated: December 17, 2025