It doesn’t happen very often, but every once in a while all the major search engines decide on something together. A week ago something like this happened and they decided on supporting canonical links in pages.
Is this useful for you? That really depends on what you are doing on the web. But for example at my work this really helps a lot. At ilocal.nl we have different ways of linking to company detail pages. For example:
http://www.ilocal.nl/WebDisplayServlet?iqk1=466448876390121&iqf1=id&tid=DetailsDisplay
http://www.ilocal.nl/nl/restaurants/bistro-zilverzoen/290448876390948
Above links contain exactly the same information. The only difference is that the first one is the old URL that we used to use. And then we switched to the second URL for SEO improvement. But /WebDisplayServlet links still get a lot of traffic from pages linking to them.
Now what you can do with canonical links is when the first URL is requested, add the following HTML in the head of the page:
<link rel="canonical" href="http://www.ilocal.nl/nl/restaurants/bistro-zilverzoen/290448876390948"/> |
This way all our friendly search crawlers can instantly recognize that it shouldn’t put this URL in it’s index, but use the canonical link. If the search engine then starts crawling the link provided here or if it’s using the data from this page, isn’t 100% clear to me. But if the page is accessed by the second URL then you should not put this canonical link in. So the crawler doesn’t try to look up a page that it’s already looking at.
One problem with this canonical link is that the content of the page should be the same or close to the same as the page that the crawler found the link on. But for ilocal what I would like to do is when a users searches for something. Then let the canonical link point to a static result page. For example if a user links to a search for “hotel zwembad” in “utrecht” (link). Let the canonical link, link to the rewritten results page for hotels in utrecht (link). But in the blog post on google about the canonical links it says the following:
Is it okay if the canonical is not an exact duplicate of the content?
We allow slight differences, e.g., in the sort order of a table of products. We also recognize that we may crawl the canonical and the duplicate pages at different points in time, so we may occasionally see different versions of your content. All of that is okay with us.
So right now I will not provide a canonical link on the results pages of ilocal.nl, but it would be nice to also have a way to specify some sort of parent URL which you want crawlers to use instead of all the URL which is cluttered with refinements by users and other nasty parameters. It’s a good thing that in the next release of ilocal.nl we will remove a lot of defaulted parameters and this might help a bit as well.
