Programming Blog

Jeremy Morgan

Mostly Coherent Ramblings of a Silicon Forest Software Developer

Google Announces the Canonical Tag

Author: Jeremy Morgan

Thursday Google announced support for the “canonical tag” which is essentially a tag to tell Google and the other two search engines which version of a url you want crawled or indexed. In theory, this should help with duplicate content issues, but is this something you want to try?

From Google:

Carpe diem on any duplicate content worries: we now support a format that allows you to publicly specify your preferred version of a URL. If your site has identical or vastly similar content that’s accessible through multiple URLs, this format provides you with more control over the URL returned in search results. It also helps to make sure that properties such as link popularity are consolidated to your preferred version.

Read their full blog post here.

Why are they doing this?

Well, by now we’ve probably all heard Eric Schmidt call the internet a cesspool and we all know about issues with duplicate content. If I understand this correctly, Google is trying to take steps to clean up some of this duplicate content, and asking the public for help.

Why you should consider doing it

I’m going to jump right into the “human reviewing” factor. Forget about the technical side for a minute. Ostensibly by creating this tag, you’re telling Google what content to grab, and you’re being somewhat transparent as a webmaster and letting them know you aren’t trying to game the system with doorway pages and multiple entry points. To the human reviewer, you are saying “Here is the page I want you to look at, and the other pages are duplicated beyond my control”. At least that’s one theory.

From a technical standpoint, you’re cleaning up their index of your page, and weeding out any duplicate content, which could make your remaining pages rank much better.

Why you should consider not doing it

Again, from the human reviewer standpoint: do you really want to let Google know you’re trying to SEO your site? Google has said time and time again, Make pages primarily for users, not for search engines. So in way, this goes against their own code, and do you want the human reviewers to know you’re doing SEO on your site? If the reviewers start searching for sites who are adopting this tag early, do you want to come up on their radar? That’s a question you have to ask.

From a technical standpoint, why do you need this tag anyway? You should be working hard to prevent duplicate content on your own, and not need this tag. Duplicate content is something that’s under your control, and something you should have a handle on if you’re concerned. If you’re using some sort of CMS or other software on your site, is the time or money you’re going to spend implementing this tag into your pages worth more than the time you’d spend fixing the problem in the first place?

Another good use for this tag

I have another good suggested use for this tag that’s a little outside the box. If the implementation of this tag goes smoothly, you could use it to your advantage. Right now, if you were to go out and buy 20 domains with established traffic, and funnel them all to your homepage, you’d get penalized good. But this tag could help you do that.

Let’s say you are working on methods of acquiring traffic that have nothing to do with Google (I know, I know but it’s possible)? This tag could help let them know you aren’t trying to game them. You could buy different urls for marketing purposes, and point them to the same site without penalty. If you have a domain that doesn’t quite fit in with your marketing, you could go buy one that does, and point it. Or, if you have a section of your site that could almost be another domain in itself, you could point a domain to it, for your offline marketing and not be penalized.

This is all theory, I don’t know for sure if you would be penalized for it, but it would be a nice side effect of this tag that I would like to see.


In the end, its your decision whether to implement this tag, and I hope I’ve given you some things to think about before doing so. Personally, I’m going to wait it out for a while and see if I can get a little more information before making a decision. We’ll see how it goes.