Canonical URLs and tags can cause confusion for many, but it doesn’t have to. Here’s our 900-word guide on SEO best practices for canonical URLs in 2018.
Canonical tags have been around since about 2009 and there are many different things a canonical URL means.
What is a “canonical” URL?
Basically, this is our way of telling Google and the other search engines this is the URL we want to index and rank. There are other URLs that may have similar content or are serving a similar purpose (including exact duplicates). Regardless of why those URLs exist, we want to direct search engines to the right one. A canonical URL ensures that search engines direct users to the right page.
URLs Pickup Parameters
Perhaps you’ve seen unfamiliar links to your site that you know direct to perfectly good content. yourbiz.com/a?=twitter, for example, may link to yourbiz.com. The ‘a?=twitter’ is a URL parameter. URL parameters do not change the URL destination or content on the page.
This poses a problem for Google. Google knows both links have the same content and doesn’t know which URL to use. This is bad for you.
We don’t want Google to be confused, so we would use this canonicalization process to resolve it. It would mean using the rel=canonical tag on the page to communicate this to search engines.
As a note, the rel=canonical tag can be used cross-domain so that if the content is found on two sites, you can direct Google to the original version. When Google crawls this other site, they will know this is the original version. How cool is that?
Two Best Ways to Canonicalize Multiple URLs and Some Things to Avoid
There are different ways to canonicalize multiple URLs. We’ll talk about the two most popular ones today and also about some things to avoid.
This is one of the most strongly recommended ways to denote a canonical URL.
The 301 redirect is a clear message to Google that: “You know what, I am going to point this URL /b to /a and I want you to forget that /b was ever a thing.” In short, you don’t want anyone visiting /b and you don’t want it clogging up analytics with visit data. Use a 301 redirect to point the old URL to the new.
Use Passive Parameters in Google Search Console
A less popular way of handling canonicalization is utilizing the Google Search Console to make certain kinds of parameters passive. This is done through the Search Parameters section of the Google Search Console. Your site must be verified!
Maybe you have several URLs with different session IDs (sessionid=lotsofcharacters), that can be marked as passive. This can be set on certain types of URLs and just tells Google: “Hey, when you feel this URL parameter, just treat it like it doesn’t exist.”
Some Things We Don’t Recommend
Blocking Google from crawling one URL but not the other version.
If you block Google from crawling your page /b, Google will only ever understand your page /a, and will not understand you have multiple links with the same content. Make sure that Google knows you have multiple links and the right way to index them.
This means ranking signals from your page /b will not be passed on to page /a. If you canonicalize in one of the ways mentioned, you will be telling Google: “Yes, /b is the same as /a, combine their powers and give me all the rankings ability!””
Don’t block indexation either.
Blocking indexation of the duplicate page ultimately results in the same problem, and relies on Google to automatically canonicalize the URLs. We do not want to trust them to do that.
We really, really want to combine the forces of pages /b and /a without risking a loss of rankings. We dont’t recommend leaving this to chance.
Don’t use 30x redirects other than 301
301 is a permanent redirect and the one Google suggests using for canonicalization. That’s what we’re going for here, so let’s follow their suggestion.
Do NOT 40x the non-canonical version
Any ranking signals your page would have had would be lost in a 404. The only time you’d want to use a 404 is if the page was created in error, or you don’t believe it has any ranking signals. In all other instances, use a 301 or the rel=canonical tag.
When to canonicalize URLs
- If the content is extremely similar or exactly the same.
- If the content is serving the same (or nearly the same) searcher intent (even when the keyword targets vary a bit).
This means if you have two unique pages with similar phrasing and sentence structures, you should canonicalize.
It’s really important to stay focused on searchers intent when determining whether you need to employ the canonicalization process. If the content on various pages is serving the same or nearly the same searcher intent, even if the keyword targeting is slightly different, you want to canonicalize those multiple versions. Google will do a much better job with one piece of content when allowed to combine ranking signals than it would trying to split those signals up across more pages and keywords.
- When you’re publishing, refreshing, or updating old content.
If the product, service, content or event is no longer available and there is a near best match on another URL.