W3C HTML Validation Service is a free tool that is invaluable for spotting hidden coding errors. As you can see, the W3C validator instantly caught this problem and flagged it as an error, in red.

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.

W3C and WHATWG finalize split on HTML5 spec, forking ‘unlikely’ The W3C and WHATWG are splitting editing duties on their respective HTML specifications. While some believe that the change will ...

However, the Web developer and design communities have called for the W3C to renew its commitment to HTML by adding new features, officials with the organization said.

Five months after reorganizing its Web services work, an influential standards body has released a trio of drafts related to the much-hyped trend. The World Wide Web Consortium ( W3C) this week ...

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.