Only valid W3C markup will do

Thank goodness for the W3C.  The W3C has set the standard for what proper coding is, and all layouts need to conform to this web standard to achieve maximum usability.  The W3c validation service is of fundamental importance to website owners both in terms of accessibility and useability.  Websites need to be accessible not only to users, but to friendly web spiders used by search engines such as Google and Yahoo.  A page that has been validated by the W3C ensures your website structure is to the current web standards.  The W3C is the source that markup such as HTML, XHTML, XML, CSS, DOM standards and more derive from.