The issue of whether or not to validate the HTML code in a web page has been controversial for several years. Whiles some SEO professionals maintain that properly validated code can help a web page to rank higher, others call that bunk.
For those not familiar with W3C validation, the World Wide Web Consortium (W3C) is the organization that sets the standards for HTML/XHTML code. They offer on online code validation tool called the W3C Validator that can be used to make sure that the code used to render a web page meets the standards.
The issue with respect to SEO has always been one of whether or not validation of a web page improves the chances for higher rankings in the search engines. Part of the controversy is based upon the knowledge that Google’s own very sparse home page displays 35 errors when tested by the W3C Validator. Matt Cutts, one of Google’s quality engineers, helps to explain the issue from the Google perspective in the following video.
As Matt explains, Google does not award a site a higher rank position because it does validate and they are very forgiving regarding the vailidation issue. We have seen figures estimating that 40% of the web pages on the Internet do not validate. From our expereince, the 40% figure is probably a very low estimate. The fact is that most web pages will show some errors because coding standards have changed over the years. Most web designers and developers do not strictly adhere to each standard because it only rarely affects the proper rendering of a web page.
While different code standards are set for each version of HTML or XHTML as determined by the Doctype tag set at the top of a web page, browsers are designed to work pretty much the same with most standards. There are some exceptions due to differences in the way that different types of browsers and different versions of browsers display a page.
Does validation matter at all?
While we have never claimed that HTML/XHTML code validation will improve a site’s rankings, we do see a value in at least randomly checking web pages and fixing the errors that are identified.
- There are some coding errors that we have seen over the years that prevent a web page from being indexed properly. Those are rare, but they do occur and they may not cause a problem with the rendering of a web page. The W3C Validator easily identifies those errors.
- When the code on a web page meets the standards and the code is written efficiently (The W3C Validator does not identify efficiency issues), a web page will render quicker and more reliably across a range of different types of browsers. Most modern browsers have two rendering engines called standards mode and quirks mode. When a page meets the standards, it is displayed using the standard rendering engine. When a browser becomes confused by the code, it may switch to quirks mode, which is intended to provide compatibility for older coding standards. The problem with quirks mode is that it is quirky and may produce erratic rendering results.
- A lot can be learned about coding standards by addressing the issues identified by the W3C Validator. This, in turn, creates awareness so that coding standards are more strictly adhered to with future programming projects.
- Most identified errors are not critical and many can be ignored. Many are due to “browser extensions” that do not meet the standards. There are many Microsoft browser extension that at one time added display enhancements to a web page. These were developed before CSS (cascading style sheets) was adopted. Today, these extensions are obsolete, but are still commonly found on web sites that were developed five or more years ago.
So from our perspective, the bottom line is that proper code validation may help pages to render properly across a number of different browsers and it may identify coding errors that could lead to poor spider indexing of a web page. The W3C Validator can therefore be a worthwhile tool to use to check the home page and randomly check several inner pages in a site to see if there are any coding issues that need to be addressed. Unless you use a tool like this, you will probably not be aware of potential rendering or spidering issues with a web site.