While CSS is a field of endeavor all its own, we'll get started with some foundations.
Cascading Style Sheets (CSS) is a recommendation developed by the World Wide Web Consortium (W3C). It originated in 1994 when Håkon Wium Lee, working at CERN (the birthplace of HTML), published a paper titled Cascading HTML Style Sheets. It was a bold move at the right time. By then, the Web was four years old and growing quickly, yet there was still no consensus for a standard style description language. The architects of HTML knew that the language was in danger of becoming a style description language if something like CSS wasn't adopted soon.
The goal was to create a simple yet expressive language that could combine style descriptions from different sources. Another style description language, DSSSL, was already being used to format SGML documents. Though very powerful, DSSSL was too big and complex to be practical for the Web. It is a full programming language, capable of more precision and logical expression than CSS, which is a simple language, focused on the basic needs of small documents.
While other stylesheet languages existed when CSS was proposed, none offered the ability to combine multiple sources into one style description set. CSS makes the Web truly accessible and flexible by allowing a reader to override the author's styles to adapt a document to the reader's particular requirements and applications.
The W3C put forward the first CSS recommendation ...