Style sheets describe how documents are presented on screens, in print, or perhaps how they are pronounced. W3C has actively promoted the use of style
sheets on the Web since the Consortium was founded in 1994. The Style Sheets Activity has produced two W3C Recommendations (CSS1 and CSS2) which are widely, although not consistently, implemented in browsers.
By attaching style sheets to structured documents on the Web (e.g., HTML), authors and readers can influence the presentation of documents without sacrificing device-independence or adding new HTML tags.
The easiest way to start experimenting with style sheets is to find a browser that supports CSS. Discussions about style sheets are carried out on the
www-style@w3.org mailing list and on news:comp.infosystems.www.authoring.stylesheets.
Cascading Style Sheets, level 1 (CSS1) became a W3C Recommendation in December 1996. It describes the CSS language as well as a simple visual formatting model. CSS2, which became a W3C Recommendation in May 1998, builds on CSS1 and adds support for media-specific style sheets (e.g. printers and aural devices), downloadable fonts, element positioning and tables.
CSS3 is currently under development. You can follow its progress as new drafts are published.
DSSSL is a document tree transformation and style language with many adherents in the SGML community.
W3C has launched a Working Group to develop the eXtensible Style Language (XSL). XSL builds on DSSSL and CSS and is primarily targeted for highly structured XML data which e.g. needs element reordering before presentation. For more information on XSL see the W3C XSL resource page.
Dynamic HTML is a term used to describe HTML pages with dynamic content. CSS is one of three components in dynamic HTML; the other two are HTML itself and JavaScript (which is being standardized under the name ECMAScript). The three components are glued together with DOM, the Document Object Model.