The web's governing body has launched a new validation tool called Unicorn that checks the quality of your website's code against multiple web standards at once.

The MarkUp Validation Service checks for compliance with different HTML versions and the emerging XHTML standard—an evolutionary change to HTML markup that's XML-compliant.

The MarkUp Validation Service checks for compliance with different HTML versions and the emerging XHTML standard—an evolutionary change to HTML markup that's XML-compliant.

Per this new agreement, the W3C is officially giving up publishing future HTML and DOM standards in favor of the WHATWG, effectively giving full control back to browser vendors.

Google’s John Mueller recently stated in a webmaster hangout that W3C validation has no impact on search results.