What Is CSS?

Cascading Style Sheets (CSS) is a language that works with HTML documents to define the way content is presented. The presentation is specified with styles that are placed directly into HTML elements, the head of the HTML document, or separate style sheets.

Style sheets contain a number of CSS rules. Each rule selects elements in an HTML document. These rules then define how the elements will be styled.

Any number of HTML files can be linked to a single CSS file.