I would say yes, but only a fraction of your on-page seo. It makes sure you have alt attributes, your tags aren't mismatched, etc.
just checked my site and i have 64 Errors, 35 warning(s) , looks good to me especialy when the site makes 5 figures a month
I always aim for valid code, but it doesn't seem to make much of a difference to SEs (imo). The Big G ain't even close to valid..
if your site valid the web standard, load fast and more stable, why not even it doesn't matter about SEO.
Having a W3C validated site will help avoid any browser compatibility and other issues. So in directly, this will help. But, W3C validation do not have any direct impact on ranking of sites in SERPs. You can see that Google homepage have many errors if you check in W3C.
it doesnt have much value, only if you have really critic errors that confuses the serp. i have seen top rated sites with houndreds of w3 errors
Clean valid code is a good thing for spiders and site visitors, so although it has no direct SEO value, I believe it should be done. In the early days, the w3c checker was being crawled. So by having a validation link on your site, G's crawler would follow it and find a nice link on the w3c site back to your original page. Well, eventually G caught on and now ignores BLs from the checker. So if someone is telling you that validation is a great trick, their info is about 6 years too late. /*tom*/
Google.com has 42 errors and 2 warnings... As noted previously, using valid HTML is important for browser support but it won't impact SEO much unless the code is just simply so bad the bots can't crawl the site.
If your site is valid then you have a higher chance of ranking better in SERPs than non validated sites. Google worries more with speed and compatibility with ALL browsers than validating in w3 for firefox alone (Ffirefox was just used as an example). Most people optimize their sites for Google so it is important that they validate. It makes no sense for Google to optimize their sites for themselves If you validate your webpages over time the quality of pages on the web will improve.