I’ve been asked about the mobile-friendly tag in search and noticed two common mistakes that I wanted to share. Both of these result in the Mobile-Friendly Test showing that a page isn’t mobile-friendly, but the PageSpeed Insights tool showing that it’s ok: Too much blocked by robots.txt. Googlebot needs to be able to recognize the mobile-friendliness through crawling. If a JavaScript file that does a redirect is blocked, if a CSS file that’s necessary for the mobile version of the page is blocked, or if you use separate URLs and block those, then Googlebot won’t be able to see your mobile site.

I’ve been involved since we first started testing authorship markup and displaying it in search results. We’ve gotten lots of useful feedback from all kinds of webmasters and users, and we’ve tweaked, updated, and honed recognition and displaying of authorship information. Unfortunately, we’ve also observed that this information isn’t as useful to our users as we’d hoped, and can even distract from those results. With this in mind, we’ve made the difficult decision to stop showing authorship in search results.

We’ve been doing lots of work to clean up the visual design of our search results, in particular creating a better mobile experience and a more consistent design across devices. As a part of this, we’re simplifying the way authorship is shown in mobile and desktop search results, removing the profile photo and circle count. (Our experiments indicate that click-through behavior on this new less-cluttered design is similar to the previous one.

Authorship works fine with Google+ custom/vanity URLs. I’ve seen this come up more since custom/vanity URLs for Google+ profiles have become more popular. Authorship works fine with vanity profile URLs, it works fine with the numeric URLs, and it doesn’t matter if you link to your “about” or “posts” page, or even just to the base profile URL. The type of redirect (302 vs 301) also doesn’t matter here. If you want to have a bit of fun, you can even use one of the other Google ccTLDs and link to that.

Dear webmasters, if something goes drastically wrong with your hoster, and you can’t host your website anymore, please return a “503 Service unavailable” HTTP result code. Doing so helps search engines to understand what’s up – they’re generally more than happy to give your site some time to catch up again. Returning an error page with “200 OK” will result in us indexing the change of content like that (and if all of your pages return the same error page, then we may assume that these URLs are duplicates).

HELP! MY SITE HAS 939 CRAWL ERRORS!!1 I see this kind of question several times a week; you’re not alone - many websites have crawl errors. 404 errors on invalid URLs do not harm your site’s indexing or ranking in any way. It doesn’t matter if there are 100 or 10 million, they won’t harm your site’s ranking. http://googlewebmastercentral.blogspot.ch/2011/05/do-404s-hurt-my-site.html (archive.org) In some cases, crawl errors may come from a legitimate structural issue within your website or CMS.

Q: Does Google allow spaces in URLs? A: Yes! But because other sites sometimes have problems with linking to URLs with spaces, we generally recommend using dashes (-) or underscores (_).