Cascading means that styles can fall (or cascade) from one style sheet to another. The cascade is used to determine which rules will take precedence and be applied to a document.

For example, rules in author style sheets will generally take precedence over rules in user style sheets. Rules in user and author style sheets will take precedence over rules in the browser's default style sheet.

Where Does CSS Come From?

CSS is a recommendation of the World Wide Web Consortium (W3C). The W3C is an industry consortium of web stakeholders including universities; companies such as Microsoft, Netscape, and Macromedia; and experts in web-related fields.

One of the W3C's roles is to produce recommendations for a range of aspects of the Web. CSS1 became a recommendation in late 1996, CSS2 became a recommendation in May 1998, and CSS2.1 became a recommendation in January 2003.