I have seen first hand the benefits of how well the rel canonical link tag works at cleaning up on-domain and cross-domain issues with the indexation of duplicate content in the search engines. Just see my post about how it helped save one of my clients – Update on Rel Canonical Link Tag Element.
The consistent theme with all of the implementations of rel canonical is that it is always after an issue pops up. Granted the tag has only been in existence since February 2009 but that is over a year ago and the tag is still not being used to it’s fullest.
Here is what I am proposing to everyone – require your developers to implement the tag on your site.
Here’s 5 reasons why you should require it?
1. Ward off scraper and mirror sites
Scraper and mirror sites continue to be an issue. Whether it is maliciously done by a 3rd party or accidentally done by development. These sites are a trap for search engines and users to wind up in the wrong place, wasting their time and resources.
2. Focus the search engines
The search engines waste a ton of time indexing duplicate content across the Internet and this can reflect negatively on the indexation of the pages on your site. The rel canonical link tag will best instruct the search engines as to which pages are of real value. By focusing them in on the real content will you meaningfully have more control over the spiders.
3. Consolidate Page Level Authority
We all know that a 301 redirect is the most effective way at preserving link equity and page level authority. The rel canonical tag also works to the same effect at instructing the search engines as to the proper placement of link equity.
4. Being proactive rather than reactive
The potential of an indexation issue is a daily concern for any site, specifically now that the search engines are speeding up their indexing processes. So, why wait for an issue to arise and damage your site/business when it can be completely avoided through the proactive implementation of the rel canonical link tag.
5. Firefox canonical navigation icon
Firefox has a built in canonical navigation icon. If the browser detects the canonical tag on the page it will display either a gray out C icon or a blue C icon:
When the C is blue not only is it a notification that you are not on the properly canonicalized URL, when you click on the icon it will take you to the correct location. So, on cross-domain canonicalization you can recapture lost traffic on the inappropriate website.
Firefox is the first browser to offer this functionality so you should be taking advantage of it.
If anyone has anything else to add to the list, leave it in the comments. These are just the first 5 I can come up with.