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W3C Validation for SEO? Separating Facts From Fiction

W3C Validation for SEO?
Wanna-be SEO types (you know, the ones that would be better off in boiler rooms) love to pitch W3C Validation as being crucial to SEO for one simple reason; it’s easy to demonstrate to a client that a competitor’s page has 376 errors, and then compare it to the soothing green ‘Congratulations’ of having no errors on some other page that passes validation.

The visual impact of “Congratulations, no errors” from the W3C can go a long way to leaving a great impression on trusting, and sometimes gullible clients. Whether validating pages play into even half a percentage point with search engine algorithms is highly speculative.

Web standards on the other hand, offer great value to SEO efforts. Especially the W3C recommendations that enhance accessibility and semantics. However, Web standard markup goes well beyond passing a simple validation test against a strict – or in some cases – a transitional doctype.

So Why Validate at All?

Valid HTML is just one result of adhering to Web Standards. If your page passes validation, it means that in your quest to meet strict standards, you didn’t accidentally use deprecated tags or make any syntax errors. Passing validation does not measure adherence to Web Standard coding practices. I’ll say it again: Passing validation does not measure adherence to Web Standard coding practices.

W3C standard validation is nothing more than a syntax check, not a measure of how web standards compliant a Web page is (In case you didn’t get the subtle hint from the end of the previous paragraph).

So Then How Do You Measure Web Standard Coding practices?

Web standard markup is mostly about separating content (text, images and other media embedded within the proper HTML elements) from presentational data (which should be restricted to external cascading style sheets, or CSS). Presentational data consists of any code that’s necessary to alter the original appearance of an HTML file – from Arial font-families to z-index – and all attributes in between.

The only way to measure the adherence to Web standards of a Web page is to understand what Web standards really mean, and to look at the page’s source code for yourself.

Separating content from presentational data alone isn’t guaranteed to help search engine optimization efforts, but it is a step towards the issue and SEO benefits of HTML semantics.

For example, a page that uses tables for layout purposes is going against the fundamental rule of Web Standards. Table based page layouts weave presentational data throughout a page’s source code, adding a tremendous amount of code bloat, and have all sorts of other nasty effects, notably much more time-consuming and costly site redesigns.

However (and this is important), a table based layout will pass strict HTML validation. Do you see where this is going? Tables are allowed in strict, Web Standard markup. It is up to you as to whether you use them appropriately.

Now I’m not saying that using tables for layout will necessarily have a huge impact on SEO efforts, but poor semantic choices of other elements just may.

The paragraph tag will obviously not cause a syntax error in your markup. It’s one of the most basic HTML elements. But if you erroneously used the paragraph tag in place of a secondary heading or vice-versa, the validator wouldn’t know the difference, but would it make sense to use a secondary heading in place of every paragraph? Of course not. Visually, paragraph and secondary heading fonts could look similar, but they aren’t; they have very different meaning (semantics), and this is where the benefits of Web Standards on search engine optimization become clearer.

Do I even need to make a case for missing alt attributes? I didn’t think so.

Search engines, similar to other visitors of your site, need as many structural cues as possible to have the best possible chance of cutting their way through your content with ease.

Enter Semantics

Tables are semantically inappropriate for page layout; they’re suitable for tabular data. Spreadsheet stuff – not mastheads, sidebars or footers. Aside from adding a lot of unnecessary markup bloat to pages and driving up the ratio of code to content on a page, the detriment to SEO is probably negligible – on a small scale; however, for sites with tens or hundreds of thousands of pages of content, I wouldn’t leave it to chance. Especially at the development stage of a site. Going back to properly recode three hundred thousand pages of markup can reach a point of diminishing returns pretty quickly.


  • Secondary headings are semantically inappropriate for holding content more suitable for paragraph tags
  • Navigation links are effectively lists of related links, and belong in HTML list items
  • Strong and emphasized text will add clarity to text

Individually, none of these semantic choices will have a huge impact on a site’s rankings; but overall, a site that is lean on code, has clear, structural markup, and embeds a minimum level of semantics into its documents will be much easier for search engine algorithms to understand and properly index.

Understanding which elements of Web Standard markup add to the search engine friendliness of a site comes with front-end development experience. To some, that pretty validation button might seem like a neat and convenient way to measure the “quality” of a page’s source code, but the only way to measure quality in this case is through understanding.

Doctype differences

Incidentally, the main difference between transitional and strict web standard markup is certain elements and attributes have been deprecated (phased out) from strict HTML standards. In other words, if you use deprecated HTML tags, those tags will earn you syntax errors when validating against a strict doctype.

Tags such as font and center have been omitted from strict standards because they have no semantic value; they’re purely presentational elements – and presentational data should be reserved for external stylesheets, not markup.

Don’t take the easy way out!

It’s easier to show a client 0 validation errors than it is to explain Web Standards, semantics, tableless layouts and the separation of content from presentational data. Okay, you have me there.

Then again, you could just bookmark this article and give the link to your more inquisitive clients when the need arises ;)

Montreal’s Springboard SEO prioritizes usability as well as findability—for maximum online profits.

About matt

Matthew Edward is the founder of Springboard SEO, a usability-first search engine optimization company in Montreal.