Valid XHTML and CSS

What does valid XHTML and CSS mean?
XHTML is the new web-standard as defined by W3C, World Wide Web Consortium.

XHTML: Benefits
Converting from HTML to XHTML provides the website with several immediate and long–term benefits:

A painless transition to more advanced technology
The web is moving to XML, a powerfully enabling technology. Writing well–formed, valid XHTML pages is the easiest way to begin this transition. All it takes is learning a few simple rules of XHTML markup.

Cleaner, more logical markup
XHTML brings uniformity to document structure. The rules of XHTML help restore the structural integrity of documents that was lost during the web’s rapid commercial expansion between 1994 and 2001. This is critical for large, and small, organizations, whose web pages must interface with logically–marked–up documents in legacy systems and databases.

Increased interoperability
Unlike old–style HTML pages, valid, well–formed XHTML documents can easily be “transported” to wireless devices, Braille readers and other specialized web environments. Moreover, XHTML’s insistence on clean, rule–based markup helps us avoid the kind of errors that can make web pages fail even in traditional browsers like Microsoft Internet Explorer, Netscape Navigator, and Opera Software’s Opera browser.

Greater accessibility
Because they follow strict rules and avoid non–standard markup, well–authored XHTML pages are more accessible than old–school HTML pages, helping the site comply with accessibility guidelines.

CSS is widely used for defining styles, but too few use it for layout purposes.

But why? Here are a few good reasons:

• make your pages load faster
• lower your hosting costs
• make your redesigns more efficient and less expensive
• help you maintain visual consistency throughout your sites
• get you better search engine results
• make your sites more accessible to all viewers and user agents

Visual Consistency
Using Web standards also makes it extremely easy to maintain visual consistency throughout a site. Since pages use the same CSS document for their layout, they are all formatted the same.
This strengthens your brand and makes your site more usable.

More accessible
Using Web standards makes our pages much more accessible to users with disabilities and to viewers using mobile phones and PDAs to access the Web.
Visitors using screen readers (as well as those with slow connections) do not have to wade through countless table cells and spacers to get at the actual content of our pages.
In other words, separating content from the way it is presented makes your content device-independent.

Better ranking
Speaking of accessiblity, minimizing your markup and using header tags properly will also help improve your search engine ranking.
Reducing the ratio of code to content, using keywords in your header tags, and replacing header GIFs with actual text will all help your sites get better search engine results.

Need I say more?