In the latest "Webmaster Help" video from Google, Matt Cutts takes on the following question:
Is there any way Google identifies "sister" websites? For example, relationships between eBay.co.uk and eBay.com? Does linking from one to the other taken as paid or unnatural? And I'm strictly talking about good, genuine ccTLDs for businesses?
"It is the case that we try to interpret as best we can the relationships there are on the web," he says. "At the same time it's very helpful if you can tell us a little bit about what your sites are so that we ca return the correct content to users regardless of which country they're coming from. So let's look at the spectrum. On one hand, you've got ebay.co.uk and ebay.com, and we need to know that those are somehow related, and then on the other hand, we've got all the way down to somebody who has a hundred different websites all about medical malpractice or something like that."
On the ccTLD case, he adds, "It is the case that we try to figure out that those sites are related, but we are doing the best we can, and if we get a little bit more help, then we can say, 'Oh, this is a German user. They should get ebay.de or yoursite.de.' If it's a French user, they should get the .fr version...that sort of thing. So the best way to help is to use something called hreflang. You can do that inside of a webpage, where you can mark up, 'Hey, on ebay.com, a French version of this page is over here, and the German version of this page is over here, or if you don't want to have that in all the different pages on your site, you can also make a sitemap. And you can just say, 'Okay, over here is one version for a country, here's another version for a country.'"
He says doing this is really helpful because Google tries to determine where users are coming from, what their language is, and then show them the best version of your page. If you tell Google what the right versions are, they're less likely to screw it up.
He cautions that they might or might not trust links between any given sites on "any given basis." For the most part, he says, however, that he wouldn't worry about them being seen as paid or unnatural, because it's pretty normal.
He does advise against linking to all versions of the the site in the footer because it looks spammy. I'm pretty sure he's covered all this before.
When the sites aren't about different languages or countries, and you have a bunch of sites, then he says you should be a lot more careful about your linking.
Image via YouTube