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Web Standards and SEO: More Questions than Answers

- Posted by to On-page SEO


I recently came across another article about "validation" and SEO. These articles always baffle me because most of what is in them doesn't have much to do with validation or SEO. Even some of the responses in SEOmoz's ranking factors seem to show some variation in what "validation" means.

It seems to me that people may be using "validation" to mean "coding errors" or "web standards" or "best practices." What they are missing is that validation is only a test of coding errors and is not the same as web standards, which is not the same as web coding best practices.

In addition, there are many standards-aware designers who would like to think that standards matter more than they do for SEO, and a lot of confusion around what does and does not make a difference. As always with SEO, there is a lot of misinformation floating around out there. Let's set the record straight! I'll tell you right now that I don't have the answers to most of these questions. Instead, I'm asking Mozzers to help me with the answers.

What is validation?

Validation refers to a service offered by the W3C which checks your web page for compliance with their standards. It is comparable to a spell checker – it checks your page against a known set of defined rules.

If a page is valid, the validator will show a page with a green bar saying that "This page is valid" according to the standard it was developed with (HTML or xHTML, transitional or strict). If it is not valid, it will show an orange bar followed by a list of errors. Validation is simply a test: does this page pass? Yes or no. If not, how many errors are there?

As an automated tool, the validator can't possibly check for qualitative problems, just as a spell checker can't tell if you're using the words properly (web standards) or if your article is well written (best practices). A page can be valid but not standards compliant or coded according to best practices, just as a written article can have good spelling but poor grammar and writing style.

Does it matter for SEO?

Even as a standards advocate, it's obvious to me that search engines don't and shouldn't care whether a page validates or not. They're looking for the best information for people - certainly whether a page passes a validator shouldn't have a bearing on that. They should also recognize that a simple human error, such as forgetting to close a tag, could make a page invalid. As Todd Malicoat suggested in the SEOmoz ranking factors, Google isn't going to waste resources running the validator on every site.

Do they care if there are errors? Well, since we've established that they wouldn't be running a validator on every site, then they probably don't. However, validation is a test of well-formed HTML - do they care about that? Some of the references on this topic have suggested that a lot of unclosed or improperly nested tags could hinder a search bot when crawling a page. Google's webmaster guidelines state that you should "check for broken links and correct HTML," but do not elaborate on what that means.

Regardless, this is a larger issue of web standards and well-formed HTML and not one of validation per se. In order to avoid confusion we should be talking about "well-formed HTML" or "HTML coding errors," not "validation."

What are web standards?

There are many things that are covered in the W3C standards that are not tested by the validator. One of the most important is semantics: that HTML tags should be used for their proper purpose. Paragraphs are paragraphs, lists are lists, headers are headers, and tables are for data and not for page layout.

A related aspect of web standards that is not fully tested by the validator is the separation of presentation from structure and interactivity. That is, keeping the CSS and Javascript out of the HTML. There are many reasons to do this, including better accessibility and easier maintenance. (This is partially tested by the validator for certain doctypes that don't allow inline event handlers and presentational HTML such as <font> tags).

Does it matter for SEO?

It's pretty clear to me that search engines wouldn't care that much about web standards either. However, it could be that they have some things in common with things that search engines would care about.

SEO Experts: I'll turn this one over to you.

  • Does semantic mark-up matter for SEO? Could it matter more in the future?
  • Is there any SEO advantage in using CSS instead of tables for layout?
  • Are there any SEO benefits in separating presentation, structure, and interactivity (e.g. keeping the CSS and javascript completely separate from the HTML code)?
  • Could web standards be used as a quality indicator?

What are web design best practices?

Web design best practices include web standards but go beyond to include general methods for coding web pages. This would include things like simplifying mark-up, re-ordering source code, accessibility, cross-browser and cross-device compatibility, etc. All of these are good things to do with a web page, but they have very little to do with validation.

Does it matter for SEO?

It seems to me that accessibility for humans and accessibility for search engines have a lot in common. If a disabled person using a screen reader or text-based browser find their way around your site, then bots will be able to as well.

More questions for the SEO experts:

  • Do search engines ever look at browser compatibility? It makes sense that they wouldn't want to list pages that don't work for people, but do they actually do this?
  • Does too much code or too much presentational mark-up affect crawling in any way? (code-to-content ratio)
  • Does source code order matter?
  • Are there any ways in which the way a web page is coded impact SEO?

For more information on web standards and some useful links, check out Robert Nyman's comprehensive explanation of the term "web standards".

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  • podcomplex

    The only actual SEO factor I could think of here might be in the code-to-content ratio: if you use an external CSS sheet for styling, it follows that your on-page ratio will be slightly better and the content will be nearer the top of the page. If you have a really big page with lots of content, then more content will get spidered rather than CSS code (i'm not sure what the current page size for spidering is - I'd guess at least 100k). I'd say any benefits of this (if there are indeed any) are marginal anyway, in terms of ranking...

  • BruceKeener

    Very interesting post, Megan, as I have often wondered about this.

    One hint to me that SEs do not care too much about validation came just this morning. I viewed my Adsense profile, and noticed that there was a message from Google suggesting that I use the Google Search feature (instead of the standard site search button supplied by the WordPress theme I use). So, I said what the heck, and put Google's search code into my sidebar. I then ran the W3C validator, which I do after any change to code, and lo and behold there were 17 validation errors, whereas there were 0 before the change.

    So, I speculated from this that Google must not care a whole lot about page validation or the Google search code would be up to the HTML 4 transitional standards, and it appears that it is not. 

  • gleddy

    great article Megan,

    I usually see the titles of an article like this and get ready for a bit of a battle in the comments section, but you have thought this out and presented both sides of the issue very articulately.

    My advice in this 'validation' argument now is to forget what Google and search engines think about validation or semantic markup.

    You will always get varied answers, mostly on the side that they don't care about markup to that detail... then Google turn around and are using Microformatted content in their Google Maps application.

    Google will not set the pace forever. We decide what is important and what we want to search for... Social media, microformats search, accessibility as SEO (gaining more users by access) and alternate methods will soon be what we are focussing on.

    Those who follow web standards ideologies will be way ahead of the game.

    thanks for the good article.

  • Michael Visser

    I'm a big standards fighter, I love seeing that green bar from the W3C and 508 "Okay" for client sites, I don't think my clients are that concerned but that's my passion.

    Incase you're lazy (or just woke up) I strongly believe the markup ("b" or "strong"), markup layout or compliance have little or no weight in SERP listings. Here's my drill down as an SEO Monkey and Front-end Developer:


    Unless you're packing text links into option elements (bad idea...) then I believe no, well-formed W3C compliant markup does not attribute to a gain in search results.


    This is an interesting point, do Google take into consideration the volume of visitors from say mobile devices, handhelds or screen projectors? Very unlikely, I'd expect this to become a factor in the future.


    I'm a standards-lover, keep it all apart, but I'm yet to see a structured site (js,css,HTML) vs. an inline site do better than the other. Any one seen any tests confirming this?

    Could web standards be used as a quality indicator?

    With 40% of the indexed Internet not being compliant (just heard that yesterday on some of Matt Cutt's old Google Video posts, want a link?) I doubt they'd apply a blanket penalty that large to non-validating sites. Cutts mentioned (along the lines of...) that there are many high-quality articles on .edu domains that don't validate, there'd be no reason to penalise sites due solely to a lack of markup skills.

    Well coded, structured and compliant markup is the responsibility of the Web developer/Front-end developer, I know in the Australian web industry this isn't a priority as the design takes a higher presedence. There is a gradual change from table-based to divisional layout designs but entrenced or overworked developers are set in their ways and resisting this new (it's 5+ years old at least!) architecture.

    Do search engines ever look at browser compatibility?

    Google spokesperson's have frequently recommended testing your site with a browser from back in 1994 (don't quote me), download a copy of Lynx (text-based browser) to ensure your site is crawlable. Recent versions of spiders also include the Mozilla page renderer. Search spiders can parse Javascript to varying degrees.

    Does source code order matter?

    Doubt it, makes your job easier though! :D


    The age old trick (now a myth?) was to structure your markup to include page content above the header and navigation. To achieve this you'd use CSS to render the page like a standard page (header, navigation, content...). Does it still work, no idea, hope not...?

    That's all, fire away any questions!

    visser edited 2007-08-01T16:31:35-07:00
  • Ian Latch

    Source Code Order can make a difference. Using absolute positioning for data that was once preceded by navigation, accessory information, etc. can now be accessed quickly and given greater prominence thanks to CSS. The other great advantage of CSS is the content-to-code ratio - which I understand is scrutinized as well. Validation is a courtesy to both engines and visitors.

  • Dax tshirts

    If you use CSS for the layout you can rearrange the XHTML so that the most relevant content comes first. You can drop the code for the navigation and header below the important stuff. I believe search engine view what comes first as more important.

    Dax tshirts edited 2007-08-08T14:32:47-07:00
    • Mike Tekula

      I'm definitely in agreement with that.  That's one of the great powers of CSS.  I've done this for client sites many times, and I believe as well that it has helped boost their rankings.  On top of that if you're using CSS properly your code will be quite clean and will maintain the natural hierarchy and relevance originally intended for HTML.

  • Pete Wailes

    Probably not now, but I think in the future it'll be more important, as there are more and more sites created, and there are greater numbers of relevant, rank-worthy sites, with fewer factors to make one better than the other between them.
    From my tests, yes.  It's small but it's definately there.
    Same as above.  It's small, but there seems to be a difference.
    • Could web standards be used as a quality indicator?
    Probably not.  Too much out there isn't compliant.
    To an extent, I think they do.  I'm guessing the spiders are clever enough to "see" a page in IE, FF and Safari, and to see if there are any differences in how they would each render a page.  If the differences are big enough, they may not give any points, but I don't think they'd mark it down.  May do in future though.
    Maybe in a small way, but I think it's more down to the why those things are there - the person isn't future-proofing the site, and it's an out-dated way of working.
    • Does source code order matter?
    For SEO purposes, I wouldn't have thought so.  It's just good practice.
    There's the obvious ones of unique page titles and meta descriptions, use of a robots.txt or meta robots, and all that jazz.  But I'm not sure to be honest.  I'd expect there probably are, in terms o

  • Associate
    Mike Tekula

    Bah - I was hoping that lame post wouldn't show itself again!

    Notice that the "blogger" references an article I'd written on validation as a factor in SEO - he scraped this content without giving me proper credit via the "about the author" section. I never "sent Search Engine Journal a write-up of the importance of valid source code." He grabbed the article from a syndication web site (probably

    I commented on the post, called him out on scraping my article without crediting me with a backlink and argued against his stance. He deleted my comment - that should tell you something.

    My confession: the article wasn't very accurate. It obviously doesn't site any authoritative sources. It was pulp. I wrote it in a half hour. I wrote it as an amateur, and the company I worked for at the time wanted me to syndicate it for backlinks. I did so, and I regretted it afterwards. Not an argument I want to staunchly support at all.

    My own take on validation as it relates to SEO: it's worth taking a look at some point. If your source code is causing the W3C validator to kick out 300+ errors there's a good chance you're making lots of mistakes. If there are problems with your code there's a chance that crawlers won't be as forgiving as browsers - they'll view your page, but they may skip over problematic areas in the code that are heavy with errors. Do I know for certain this happens? No, but I have to imagine Googlebot isn't going to waste time and resources trying to sort through your crummy code.

    Errors in the source code aren't always catestrophic. Many of them, in fact, won't affect the display of your page at all - and probably won't affect the crawlers. Should you spend all day validating your source code? Probably not. I like to validate mine, because doing so gets me in the habit of coding properly. The code I write now comes out error free almost every time. Validating is also a great way to get comfortable with HTML, XHTML or whatever you may be coding your pages in.

    But here's the bottom line: there are many other things to look at first. Validating your code is nice, it can uncover coding errors that may impede crawlers to an undisclosed degree - but from an SEO standpoint I wouldn't put it at the top of the priority list. It may, in fact, not be on that list at all.

    MikeTek edited 2007-08-01T22:35:37-07:00
  • zerocattle






  • diaryku

    i am new to this seo discussion and, i don't know more about what better seo for my blog. I've tried testing to validate my blog with css validator and it has many error but my blog is still able to be found in the top ten google SERP

  • Associate
    Mike Tekula

    One more thing about that article and blog post:

    It shows you how skeptical you need to be reading these things.  I happen to be personally responsible for the article that was the sole reference for that blog post.  I can tell you the following about it:

    • The topic and argument were dropped on my desk
    • I was the "content mill" in the office at the time
    • Most of the content that came through to me had been scraped from other sources
    • I have since quit that job because of unethical practices like this 

    You should be skeptical whenever reading something from a less-than-reputable source like this.  There are a lot of webmasters out there trying to pump content into their pages as quickly/easily as possible - and there are only a handful of true, reliable authorities on the topic of SEO in my opinion. 

    That blog post, for example, was made up primarily of the article - the blogger had little work to do in that case.  He was padding his blog with content  like so many do.  Hardly a reliable source of information.

    • Megan

      Hey Mike,

      Don't worry about it! I'm sure we've all written content that we hope never raises its ugly head again. I knew that the article was pretty shady when I saw it so thanks for clarifying things. I actually had a nofollow on that link before I noticed that they were going to nofollow all links in there anyway.

      Content like that is one of the reasons why I wrote this article (and continue to write a bit of what I know about SEO for other sources, usually full of links to SEOmoz since I'm obviously not a reliable source!). Many people would come across something like that and not be skeptical! I see it all the time in the forums I run. There's so much mis-information floating around out there, and it's hard to clarify with people because they don't seem to see the difference between the reputable sources and the cruddy ones. Or even pay attention to the reliable ones when they are pointed out.

      Megan edited 2007-08-02T08:40:38-07:00
  • Megan

    By the way, I'm thinking that the answer to most of these questions is probably "no" or "very little", but it would be good to have an authoritative reference for when the topic does come up. I know some webmasters who do believe that standards are better for SEO (not because google cares about standards per se, but more because they care about some of the effects).

    Megan edited 2007-08-01T13:41:57-07:00