ADVANTAGES OF USING XHTML AND CSS

The latest standards will allow the web designer to:

• Attain more precise control over layout, placement, and typography in graphical desktop browsers while allowing users to modify the presentation to suit their needs
• Develop sophisticated behaviours that work across multiple browsers and platforms
• Comply with accessibility laws and guidelines without sacrificing beauty, performance, or sophistication.
• Redesign in hours instead of days or weeks, reducing costs.
• Support multiple browsers without the hassle and expense of creating separate versions.
• Support nontraditional devices, from wireless gadgets and web-enabled cell phones to Braille readers and screen readers used by those with disabilities—again without the hassle and expense of creating separate versions.
• Deliver sophisticated printed versions of any web page, often without creating separate "printer-friendly" page versions or relying on expensive proprietary publishing systems to create such versions.
• Separate style from structure and behaviour, delivering creative layouts backed by vigorous document structure and facilitating the repurposing of web documents in advanced publishing workflows.
• Transition from HTML, the language of the web's past, to the more powerful XML-based markup of its future.
• Ensure that sites so designed and built will work correctly in today's standards-compliant browsers and perform acceptably in old browsers (even if they don't render pixel-for-pixel the same way in old browsers as they do in newer ones).
• Ensure that sites so designed will continue to work in tomorrow's browsers and devices, including devices not yet built or even imagined. This is the promise of forward compatibility.

- from Designing With Web Standards by Jeffrey Zeldman