Great article. I always strive to ensure my websites are 100% validated to Transitional but i never really bother with Strict as I don’t see any real benefit to this.

I agree its important to aim towards 100% but if I wanted something on a site which would cause the site to become invalid, I would try to find a work around but I certainly wouldn’t lose any sleep over it!

Thank you so much for this insightful article! After the w3c checker battered me with red notifications that my website had not passed any of its tests – even though it only showed 9 seemingly small style problems – it was like a balm to my soul.

The site itself has been performing well but, in the interests of trying to toe the official line for my client, I have just spent two hours trying to eradicate the errors in other people’s plugins and codes whilst retaining the feel of the page in Chrome and Firefox, only to discover that IE seemed to be using a code to which I clearly had no access since it certainly wasn’t obeying any commands that I had given it

Add to that the disclaimer on the w3c site that it is ‘not always reliable’!!!

I was so incensed at the waste of my time that I decided to write a post about w3c but, there in my notes which have accumulated on the subject over a period of some months, was a link to your post… resulting in the resuscitation of my sanity.

Thank you

But full 100% compliance is not an SEO requirement. Matt Cutts from Google has even come out and said that fully compliant code is not a ranking factor. As I say in my article, as long as the code is clean enough to distinguish style, navigation, and content, that’s as far as is necessary from a purely SEO point of view.