by: Rev Sale
13 October 2009:
You read that right, condom. Because condom equals protection. And it's an unsafe web.
Now that I've provoked you, let's see how this new tag is being used.
The marketing team loves the new link canonical tag, once they discovered that they could use it to manipulate existing ranks - not to create high ranks, but to REPURPOSE existing high ranks. So we can now easily replace that old, ranking product page with the new product page, just in time for Christmas. But I'm getting way ahead of myself here.
The concept of the canonical url is as old as the internet. It's the notion that ONE url has the all the necessary ingredients to produce the page in question, even though there may be other urls that produce an equivalent page in a browser. It's that notion of oneness that's not only Zen, but also identifies the uniqueness quality that Google so dearly loves.
This could be the page that runs the script. Or a product page that paginates. Or a product url that all your affiliates use when they add their tags to your url.
The point I'm making with the "condom" nomenclature is that we're finding this tag protects you from some nasty consequences that could be plaguing your site right now. For one, it protects you from the actions of your affiliates by forcing the recognition of your canonical url, even when it gets slammed with parameters and tags.
If you have secure pages, the link canonical on every page can protect you from accidentally getting your entire website indexed twice - once as http and the other as https in Google's main index. Can't tell you how many Google penalties were remediated this way.
And just posting this tag on your homepage can have a beneficial consequence. There are many implementations where the cms automation is creating undiscovered redundancies. Whether it's index.html, default.asp, home.php, or any other, the link canonical tag can wipe away decades of non-compliance. We've got plenty of client experience to support this observation - sites whose homepage was suppressed suddenly starting to show strength after being tagged. It is now our recommended practice to use the link canonical tag on every page of the site.
So whether or not you understand any other strategy we're about to discuss here, USE this tag for protection.
Some Ways You Can Benefit From The Link Canonical Tag
- If you have one article about a product, but your store gradually grew so that those blue widgets now need 5 pages. The problem is that the same article is on all 5 pages. The link canonical defining the entry url for all these pages allows Google to ignore the redundancy, because all 5 pages are seen as the same page.
- If you've seen https pages in your index, you really need this tag. Just posting it on every page will wipe out all https urls in the index. We've pulled sites out of penalties with this technique.
- If you've ever seen urls created by affiliates in your index, use the link canonical to wipe those out. These unwanted urls getting indexed are never good for your ranks, and while they may not get your ranks suppressed, they can still harm your ranks INCREMENTALLY.
- Need to get your new product page to the top of the search? You can do it if you already have the old product page ranking. Clone the old page, add the new product content, add the new page canonical to the old page & the new one. Upon next indexing the ranks should swap. There are some caveats here - and we've seen some weird results sometimes. But the experiments are basically working, and the results are very consistent when your pages really are close. Once the rank swap occurs (you'll notice that the old page will fall out of the index), redirect (always do this) and delete the old url.
Firefox now indicates whether or not you're on the canonical url. Note the gray "C" in the url bar when you visit this page - that indicates that the page in your browser is the canonical url:
But is blue on this page:
Go look at the source code and see the canonical is the same on both pages.
Paying attention to this indicator can help you implement properly. For example, if you leave off the trailing slash (eg http://www.yoursite.com - should be http://www.yoursite.com/) you'll see a blue "C" instead of the correct gray color.
The link canonical is a hybrid of a redirect (a mod rewrite) and a content/PR aggregator. I'm running experiments to see if the PR is aggregated along with content, and the consequences of chained canonicals - for example what happens when you swap out the ranks a number of times. Does the inbound PR suffer like in chained redirection? Should we count the number of swaps? So many questions!!
Send us your experiments, please.