The W3C is an organisation set up by the major players on the internet (particularly the web browser developers) to decide on standards for the different web languages, such as HTML. For anybody who remembers creating websites in the early days of the web, before the standards, you will realise how important these standards are.
But what does it mean to you as a website owner?
To understand this, you need to understand how HTML works. HTML is the computer language that your website is written in, under the covers. When you are editing your website, the tool that you are using converts your changes into HTML, and stores that. When someone visits your page, it is the HTML that gets sent to their web browser. Their browser then understands the HTML and converts it back into something that makes sense to normal people.
But before all the clever tools that people have now for editing their websites, people had to write the HTML themselves. And it turns out that people aren't very good at writing HTML perfectly. They tend to make mistakes (some people a lot more than others).
So, the companies that developed the early web browsers decided to try to accommodate some of the common mistakes. To try to work out what they really meant, instead of the glaring error that they actually wrote. This was good because it meant that less technically competent people could attempt to write HTML without it being too strict and the website would still look right. But it also meant that people could be sloppy, so it effectively encouraged sloppiness.
Something else that the web browser developers wanted to do was to make their browser better than the others. So they decided to add new features to HTML that the other browsers didn't support. For example, the early Netscape browser introduced the ability to "blink" text and images (so that they flashed) and the early Microsoft Internet Explorer added the ability to scroll text and images across the page. If you used these extra HTML features, your website would effectively only work properly in one browser.
So the W3C was formed to decide on a "correct" version of HTML. Anything outside of this standard might still work, but it would be unofficial and you use it at your own risk.
I won't go into the problems with Microsoft not implementing those standards properly in Internet Explorer, that's a completely different rant!
So, in it's purest sense, it means that if your website doesn't validate against the W3C standards, then technically it's incorrect, it's sloppy. It makes your web designer look like a bit of an amateur.
But who cares if it looks OK to your visitors?
Well, here is the problem, your visitors are not just people. The search engines also look at your website, and you usually want to keep them on your side. Other websites also like to understand your website content, such as Facebook. These systems aren't really looking at your website the way a normal person does. They are just software, so they're just looking at the HTML.
In short, the better that your site validates against the W3C standards, the better chance these systems have of understanding your website correctly.
Now, they may understand your website just fine anyway. But you don't really have an easy way to find out how well all of these different systems are understanding your website. You can't see what they see. So, it's best to just keep to the W3C standards to maximise your chances.
So how do you test your website against the W3C standards?
Simply enter your website into http://validator.w3.org. This will test each web address that you enter into it, so ideally you should check all of your pages. But realistically just a few of your web pages should suffice to give you an idea of how well your site validates.
You should also be aware that this validator isn't perfect. It sometimes highlights errors which aren't really errors. Sometimes you may be using some more advanced code that it thinks is an error, but in reality is just a problem with the limitations of the validation software.
So if you have no errors, then brilliant, your site is fine. If you have a handful of errors, it's probably fine. It may just be down to one of these validator limitations.
But if you have tens or hundreds of errors being highlighted, this is possibly a sign of an amateur web designer.
Will fixing the W3C errors improve your SEO?
Well, indirectly, yes it may do if it helps the search engines to understand your website better. But the search engines aren't going to intentionally mark you down for having a website that doesn't validate properly. Even if it is one of their ranking factors (which I doubt) then it would be such a weak ranking factor that it's not worth considering.
At OpenGlobal, we test our client websites to ensure maximum compliance with the W3C standards (and many other standards) as a matter of principle. In an industry that is notorious for amateurs and cowboys, we take these things a bit more seriously than most. If you want help from a web designer that goes the extra mile, contact us today on 0845 269 9624