Since canonical tag was introduced and announced, a lot has been said about it. Rand did a great ob summarizing its features and differences with other similar tool. In short, the main differences between 301 re-direct and canonical tag can be represented as follows:
| Canonical tag | 301 re-direct |
| Used to re-direct page ‘power’ onto another page | |
| affects only crawlers | re-points all traffic |
| works only within a domain | has cross-domain functionality |
However, some SEOs doubt the tag is actually any use at all. Really, it seems to be a bad cure for the serious disease: if the site architecture is screwed by lots of (partially) identical pages, it should be fixed – applying tags to show crawlers what’s more important is not a way out.
But if you come to think about it, I start seeing some cases when this tag can be implemented.
My SEO strategy is always careful. When starting a new project to find on-site SEO is screwed there, I never recommend breaking everything and doing SEO from scratch. I prefer to move forward slowly implementing minor changes and watch the affect not to risk losing the site current rankings.
In this case, the canonical tag seem to come really in handy. It allows for changes without affecting user interface. It enables to moderately move weight from one page onto the other one. I am almost sure I am going to use the tag, what about you?
I read here that canonical tags created by SEO plugins need to used with care or they can mess your pagerann.
I will wait and watch the performance of this tag.
it should be used with care
i wrote a post about using it in blogs
everyone seems to be using it the WRONG WAY
http://centuryhouse.net/canonicalization-element/
I recently switched to WP2.7, and google started indexing comment urls, comment pages – and horror, stopped indexing altogether. After a lot of attempts, I tried a canonical plugin – and the next post onwards, indexing problems vanished.
Wait and see seems to be the correct modus operandi excepting in a few instances when 301 redirects are not appropriate (PPC landing pages that have unexpectedly gained inbound links for example)
I think there are many situations where the tag can be used. Fore example, if you have a page that displays a set of results – and filters to allow users to reorder those results (which affect the URL of the page) – you could use the tag.
There are some scenarios where only the rel=canonical tag will work.
An example would be a page that had the Google Analytics utm_ parameters in the URL. If you redirect to a URL without those parameters, you’ll break Analytics. If you don’t redirect, you’ll run into canonical issues.
More detail is available at the link in my sig.