What is XHTML strict validation, and why should I care?

First, let's cover the basics. HTML is a language that is used to display text and images across multiple computers and platforms. HTML, on it's own has many limitations, not the least of which being a poor compatibility between different browsers (think Internet Explorer, Firefox, Safari), very limited capability to style a site properly, and a lack of support for many features common today that can make web sites an interactive experience. This issue was solved with the inclusion of XML, a language developed to both increase the possibilities of and reduce the complexity of HTML. Combined, they become XHTML.

Okay, so what does this mean for me and my web site?

Now we come to the fun part, (X)HTML errors, and what they actually mean. There are many web sites out there that operate relatively smoothly on the outside, but whose architecture on the "inside" (what you see when you press the "View Source" button in your browser) is very poor. This poor architecture and these validation errors can combine to cause a number of serious problems for you and your web site, and you may not even know it's happening.

XHTML errors can cause any or all of the following on your site:

• Decrease Your Search Engine Performance
  Some validation errors translate directly into search engine effectiveness, such as the alternate tag for images. While you can see that an image on your site says "welcome to our web site!," Google sees only a blank image, UNLESS you give this image an alternate tag, which tells Google what the image is. Without validating your web site, you could lose out in search engines on every picture you have on your site.
• Slow Down the Web Site to Viewers
  If errors exist on your web site, your visitors' web browsers will have to resolve those errors and conflicts before the page can be rendered. The more errors you have that the browser has to resolve, the longer it can take a web page to load and the more likely your site visitors are going to leave.
• Change How Your Site Looks to Visitors
  Errors on your web site can harm you both in search engines and in load time, but they can also alter the way your design looks to visitors. A poorly formed web site can look different depending on what browser is being used (Firefox, Internet Explorer), or even between which version of the same browser is being used (Internet Explorer 6 or 7). Most of the time you won't even realize this if you only use one browser, but everyone else who visits will notice and go the other direction. Don't think it matters? Consider this: Regardless of what browser you may be using, chances are that at least 30% of your site visitors are using Firefox, Safari or one of the many other non-Internet Explorer browsers to view your web site. That's 30% of your customers who could be seeing a very poor looking web site, and you wouldn't even know it. If 30% sounds too insignificant a number for you to worry about, consider that many, if not most web sites don't even offer good compatibility between Internet Explorer 6 and 7. That means that you may see the site fine on IE 7, but all those viewing the site on IE 6 (or vice versa) are seeing many serious errors. Since you can have only one Internet Explorer browser (6 or 7) running on a given PC at one time, you can't simply check to see if it looks the way it should after you make a change.

How do we remedy this?

Every site that we design has been exhaustively tested in Internet Explorer 6, 7, Firefox (both Windows and Mac versions), and Safari (Windows and Mac). Before you ever see your new design, it will have been extensively tested on multiple computers and proven to be identical, across all browsers. In addition, every web site we create is XHTML Strict valid. This means that we go through every page of your web site with a fine tooth comb, ensuring that there are no errors that could cost you search engine placement, load time or customers. XHTML Strict is the most stringent and highest level of validation achievable on a web site, and that's what the "Valid XHTML Strict" stamp means on the bottom of every one of our web sites. It symbolizes a web site that has been built to the absolute highest quality and standards. Learn more about how search engine effective our SE system is.

Take the validation challenge:

Ready to see how your current web site measures up? Just follow these simple steps:

1. Click this link to see the validation for this page of our web site.
2. Enter in your URL next to the "Address" box
3. Mark the Doctype as "XHTML Strict" and press "Revalidate."

Having trouble? See the outline below: