Google has a new "Webmaster Help" video out. This time Matt Cutts discusses optimizing for the mobile web. Specifically, he takes on this submitted question:
Is there a way to tell Google there is a mobile version of a page, so it can show the alternate page in mobile search results? Or similarly, that a page is responsive and the same URL works on mobile?
Cutts says this is a very popular question. Google has plenty of information on the subject out there already, but obviously people still aren't quite grasping it.
"The other way to do it is to have one version of the page for desktop and another version of the page for regular mobile smartphone users, and to have separate URLs," he continues. "So how do you handle that case correctly? Well, first off, you want to make sure that on your desktop page, you do a rel-alternate that points to the smartphone version of your page. That basically let's Google know, 'Yes, these two versions of the same page are related to each other because this is the smartphone version, and this is the desktop version.' Likewise, on the smartphone version, you want to do a rel=canonical to the desktop version. What that does is it tells Googlebot, 'Hey, even though this is its own separate URL - while the content is the same - it should really be glommed together with the desktop version.' And so as long as you have those bi-directional links (a rel-alternate pointing from the desktop to the smartphone and a rel=canonical pointing from the smartphone to the desktop) then Google will be able to suss out the difference between those, and be able to return the correct version to the correct user."
As long as you follow these best practices, he says, Google will figure it out.
The video page points to this page on building smartphone-optimized websites, which includes an overview of Google's recommendations, common mistakes, and more info about various elements of the subject.
Image via YouTube