Does Googlebot care about valid HTML?

Matt's answer:

ADRIAN MADARAS: Today’s question comes from Bangalore. Hemanth asks, does the crawler really care about valid HTML? Validating google.com gives me 23 errors and 4 warnings. So there are plenty of reasons to write a valid HTML, and to pay attention to your HTML, and to make sure that it’s really clean and that it validates. It makes it more maintainable. It makes it easier whenever you want to upgrade. It makes it much better if you want to hand that code off to somebody else. And there’s just a lot of good reasons to do it. At the same time, Google has to work with the web we have, not the web that we want to have. And the web that we have has a lot of syntax errors, a lot of invalid HTML. And so we have to build the crawler to compensate for that and to deal with all the errors and weird syntax that people sometimes mistakenly write in a broken way onto the web. So Google does not penalize you if you have invalid HTML, because there would be a huge number of web pages like that. And some people know the rules and then decide to make things a little bit faster or to tweak things here or there, and so their pages don’t validate. And there are enough pages that don’t validate that we said, OK, this would actually hurt search quality if we said only the pages that validate are allowed to rank, or rank those a little bit higher. First and foremost, we have to look at the quality of the information and whether users are getting the most relevant information they need rather than whether someone has done a very good job of making the cleanest website they can. Now, I wouldn’t be surprised if they correlate relatively well. Maybe it’s a signal we’ll consider the future. But at least for right now, do it because it’s good for maintenance. It’s easier for you if you want to change the site in the future. Don’t just do it because you think it will give you higher search rankings.

by Matt Cutts - Google's Head of Search Quality Team

Original video: