From the World Wide Web Consortium Q&A blog, article titled Craft of HTML:

HTML is a practical art. In a professional context, it requires precise and extensive skills. As with many popular crafts, the vast majority of people do it on their own, but only a few do it for a living. The quality of products varies a lot.

Bruno Pedro has recently published Top blogs fail W3C Markup Validation. He has taken the top 20 list of popular weblogs and puts them through W3C validator. None passed markup validation. Then the author is encouraging people to take care of validation. The comments following the article express either frustration, anger or support. This article is a good illustration of the misunderstanding about HTML validation.

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When you are a developer of a content management system, of an authoring tool, of a small widget, be sure to create all the fonction to sanitize the content in production and input. Maintaining the quality of your content is a better goal than a one time validation.

Reference of tools

• Wordpress XHTML Validator by Manuel Amador Briz
• MTValidate Plugin by Jacques Distler
• LogValidator by Olivier Théreaux

Incidentally, I validated my own pages and I found two validation issues related to the Creative Commons license (something about the XML namespace used by the code) so I just commented those stanzas out. Dear Lazyweb, how can I specify several valid namespaces for an XHTML document?

To the W3C staff: thanks :-). Much appreciated.

Update: Hot on the heels of 0.2.0 comes 0.2.1 which fixes a small bug for those of you who don’t have `tidy` installed on your servers.

Well, now, there’s a new reason… or, actually, it’s a pretty old one. Section 508 of the US Rehabilitation Act makes a few requirements for public Web sites and blogs, to improve accessibility for their users.

The first step, as with every Web deployment and maintenance effort, is ensuring that your site validates. Validation is paramount — otherwise, down the road, there are no guarantees that the accessibility practices and technologies on a site will actually work.

The problem with most blogs (especially WordPress) is that their contents are dynamic: content is generated, out of a database. So, it’s impossible to validate an entire dynamic site, in a practical fashion.

But rest assured, there’s a way out of this mess: for WordPress-based blogs, I’ve written a plugin named WordPress XHTML validator which lifts an enormous weight from you, the author. Using the XHTML validator, this is how you get from invalid HTML to valid HTML:

1. Validate your content: on your WordPress administrative interface, go to the Manage tab. Then click the XHTML validator tab. A fully automated procedure will validate posts, pages and comments, then present you with a list of invalid entries, which you can quickly edit by using the associated Edit links.
2. Validate your template: after you’ve validated all content, you should submit your front page, and a few archive pages, to the W3C validator. Then, manually fix the spots where your template has errors. It’s certainly possible that the WordPress XHTML validator missed some spots — at this stage, you’ll catch these errors.
3. Keep the plugin enabled: every time a new post or page is saved, a red box will warn you if it contains invalid XHTML. Good practice: save your post first, instead of immediately publishing it. That’ll give you a chance to catch any errors early.

So, that’s it for today. Get your blog valid and start working towards Section 508 compliance. Do it today: every day you gain may mean a couple thousand readers more satisfied. Keep this in mind: people don’t remember when everything went well, but they’ll surely remember when your site breaks.

Here’s my take on the issue: it’s very important.

Why is HTML/XHTML validation important?

If your content does not validate, your RSS feeds might be broken as well. Most feed readers will barf when fed broken XML/XHTML. That means fewer readers.

Validation is also important in another sense: when you focus on validation, you inevitably end up doing somethign about semantics in your markup. Everyone benefits from this, especially you, the author, because Google and other search engines benefit from semantic markup.

Plus, broken HTML/XHTML may render in unpredictable ways with different browsers. XHTML-based blogs may not even render under certain circumstances (we’re talking about the famous application/xml+html content type here). I don’t suppose you’d want to harm your readers’ reading experiences, do you?

To help you in your thankless task of ensuring that your WordPress blog always remains valid HTML/XHTML, I’ve written a special plug-in for it: the WordPress XHTML validator. Download it today!

By the way, thanks for the reference link, thTeong!