When I was in school, I learned that having my websites’ code be 100% W3C standards compliant wasn’t just something to brag about, it was something to be ashamed of failing at. It’s an attitude that I’ve maintained while working at Longevity Graphics, which has lead to some pretty frustrating days. Some of our clients’ sites use CMS’s such as WordPress, Drupal, or Perch that have their own code structure that is not compliant with W3C standards. Even social media applications such as the Facebook ‘like’ button and Google Plus buttons don’t validate!
It got me wondering whether validation is truly crucial. Specifically, I wondered how important W3C validation is for SEO. I did some research, and while I found some contrasting views, W3C validation does not seem to be an important factor for SEO – with some caveats.
Out of curiosity, I used the W3C validator to check Google’s home page for errors. The result was 34 errors and 3 warnings. It shouldn’t be surprising, however, as Matt Cutts himself has said explicitly that W3C validation does not offer a ‘boost’ to the ranking of any site (see Matt Cutts’ explanation here). If you don’t want to watch the video, I can paraphrase: Google cares more about loading times, browser compatibility, usability, and content than validation for the sake of validation. This should be enough to end any debate, but there are a few things to bear in mind even if 100% W3C validation is not a factor in itself for SEO.
The first thing to remember is that many of the factors that W3C validation is based on are also important to SEO. For instance, the use of alt tags on images is mandatory for validation and it’s also important to use relevant keywords in alt tags for SEO. So while W3C validation is not directly beneficial to SEO, there are a lot of overlapping standards. Having clean code should also help to increase load time, which is a ranking factor for Google. Improving load time will enhance the crawlability of the site (especially important for large, deep sites such as online stores with dozens or hundreds of product pages). Smaller files and cleaner code will help you to reduce the fatigue of search engines while crawling your site, so they will be less likely to time out and not index deeply nested pages.
The bottom line is that the W3C validation points out a lot of issues that, when fixed, help to keep the code clean and easier for crawlers to index. A couple of validation errors on a page is not the end of the world. However, we should take as many steps as possible to increase the crawlability of the site to ensure that all content is being indexed.