Specifying the look of your HTML documents with Cascading Style Sheets can dramatically reduce the cost of creating and maintaining a website. The appearance of thousands of pages can be changed with a few minor edits to one file.
An HTML (Hypertext Markup Language) document is comprised of a pre-defined set of elements (e.g.: headers, paragraphs, etc.) delimited by semi-descriptive tags (e.g.: <h1>Headline</h1>, <p>This is a paragraph.</p>, etc.). HTML was originally devised as a document structuring and linking mechanism, and no assumptions were made as to the precise way in which a browser, or user agent (UA), would render the various elements.
As the WWW became commercialized and personalized, authors began to demand more control over how web pages appear to their readers. Browser designers responded by defining additional HTML elements (e.g.: font) and element attributes (e.g.: align=). The problem with this approach is that documents loaded with specific styling information become virtually uneditable. Also, various 'tricks' used by authors -- such as the use of table elements to position other elements -- severely compromise the structuring information elements are supposed to convey.
CSS (Cascading Style Sheets) is a means to apply styling rules to HTML-structured documents without altering the documents themselves. For each HTML element, an author can declare various properties that define how the element should be rendered by the browser. A single stylesheet can then be applied to any number of documents to produce a consistent look and feel.
HTML can now be relegated to its original purpose. Yahoo!© 1999 Hearn/Perrell Art Associates