Here is an interesting discussion regarding code validation from a web development forum:
Q. My school board hired a professional web design company to do their new website. Out of curiosity, I ran the home page through the W3C HTML validator and came up with 116 errors. The design company’s home page has 04 errors. Do designers pay attention to this? I thought having validated pages was important–but I’m just an amateur.
A1. IMHO, there are two main reasons to make sure that your pages pass validation.
1) It helps make sure that your site will render correctly on the different browsers that visit it. This is not a guarantee by any means, but you can usually be sure that if your pages do not pass validation that there are problems in the markup that could cause you problems.
2) Having clean markup that passes validation can help to make sure that you don’t kill your self in regards to the search engines. The spiders for Google and such are just programs. They read in the raw HTML and process it in chunks (largely based on HTML tags).
If your site is a mess (with missing or incorrect/incomplete tags) then you are raising the probability that the spiders may hit a point where they determine that they can not process the page further – then they abandon it and move on.
It would be a shame to kill off the SEO of a site just because some valuable content was wrapped in a hodge-podge of HTML that caused a spider to miss it.
Since the online validators are free an easy to use, there is generally no good reason not to try and make your pages pass.
Yes it is a bit more work and a lot of web designers don’t do it, but this is usually because they are either lazy or incompetent. A professional will almost always try to make sure that the final works pass validation.
A2. In addition… let me add:
– Valid code is a whole lot easier to maintain.
– Valid code is a whole lot more likely to pass accessibility tests.
It’s more likely that the coder understands what they’re doing; if they understand what they’re doing, they’re more likely to do the slightly greater effort required to make the site accessible. You’re dealing with a school, which is a public entity. As such, in the US it’s
required to meet ADA and Section 508 requirements. Many other countries have such requirements, too.
A3. Being compliant with Section 508 laws is the last reason to write compliant code. Having websites that work as expected is a much better reason<g>