SEO Tip #144: Does Indexing A Mobile Website Create Duplicate Content?
Matt Cutts: Great question. First off let start off by saying we’ll put a link in the description of this video that points to a blog post. It was done by a bunch of people who have experience with this particular topic from the Japan team who talked about SEO, mobile, all that stuff and how they interact but let me go ahead and share the best practices with you.
Googlebot has a specific user agent, I think it is Googlebot mobile, for mobile search. So if you see Googlebot mobile, then serve up your mobile site. If you see just regular Googlebot I would serve up just your regular site. It can be nice to have the content on a separate URL, so maybe use m.whateveryoursiteis.com; that can be a very good best practice.
The other thing that some people seem to worry about is they say, “Well aren’t I cloaking? Is this going to cause some sort of cloaking issue? Will I get into a penalty from that perspective?” The answer is no for the following reason; cloaking looks at the difference between what is returned to the main Googlebot, that is our Googlebot WebCrawler, versus to the user.
So there is no problem returning your main site to Googlebot and your main site to users using a regular web browser, Internet Explorer, Firefox, Chrome, anything like that. Now if you see a mobile user agent come in, something that you can tell from the user agent is an iPhone or an Android phone or something like that then it absolutely makes sense to return your mobile version of your site.
So in essence all we ask you to do to avoid any cloaking is if regular Googlebot comes, the WebCrawler, treat us just like a regular web user visiting with Internet Explorer or Firefox or Safari or Chrome. If a regular user comes in or if Googlebot comes in and it’s Googlebot mobile, then give it the mobile version of that site.
Other than that those are the main things to bear in mind. I think it is very handy to have a separate URL, like m. whatever the name of your site is, because then you can always do testing, you can make sure that things work. It might keep it a little bit more clear in people’s mind about what’s going on.
But if you do those you shouldn’t have any duplicate content issues. And if you do please stop by the forum linked to from Google.com/webmasters and let us know what sort of issues you see and then we’ll take that, see if we can debug it and make sure that it works better for everybody.