How to use (and not use) rel=”canonical”.
by Traci Lester, Digital Marketing Specialist – ASPE, Inc.
There is a lot misuse around the rel=”canonical” tag. The intention of this post is to point out those common mistakes and explain the correct usage of rel=”canonical”. First off, what does rel mean? Rel is an HTML attribute that search engines use to establish a relationship between a link and the content it appears on. Whatever is after the equals sign (ex: <link rel=”canonical”) establishes the relationship of the content to the link that follows (ex: ‹link rel=”canonical” href=”http://www.aspe-roi.com/folder/example.php”/›). The word canonical is an adjective meaning authoritative or standard. When you use the rel=”canonical” tag on a page, you are ultimately telling search engines: 1. there is duplicate content on that page, and 2. where to find the original content. That way Google, Bing, Yahoo, etc. will index the canonical, more important page, and will not index the page with the duplicate content.
The most common misuse of rel=”canonical” that I’ve seen is using it in a paginated series and specifying rel=”canonical” from page 2 back to page 1 and so on. Remember, any time you put a canonical tag on one page back to another, the page with the tag will not be indexed. Therefore, page 2, 3, 4, etc. will not be indexed. The correct way to tag a paginated series is to use rel=prev or rel=next. If there is a complete version of this paginated series on one page somewhere, you could use a canonical link back to that page. Otherwise, you’re telling search engines that the other pages in the series are duplicates of page 1. Oops.
Another very common mistake made with rel=”canonical” is using a relative URL rather than an absolute URL. A relative URL is a shortened version of the the complete, or absolute URL. If you’re using a tool such as Adobe DreamWeaver to edit your web pages, URLs will often be automatically shortened and look something like this:
<link rel=”canonical” href=”/folder/example.php”/>
In this case, you will need to type in the absolute URL by hand so that is looks like this:
<link rel=”canonical” href=”http://www.aspe-roi.com/folder/example.php”/>
Unintended or multiple declarations of rel=”canonical” is also a mistake I see too often. How many times have you created a new page on your site by copying another page and then modifying the text? I know I do it all the time! But what if there is a rel=”canonical” tag on that page? That page will not be indexed. Or, what if there is already a rel=”canonical” tag on that page that you were unaware of and you added another one linking back a different URL than the original rel=canonical tag? More than likely search engines will ignore both rel=”canonical” tags, and you’ve created the problem you were trying to fix in the first place – duplicate content being indexed.
When I was a green internet marketing specialist fresh out of college, I had no clue where to start with my SEO efforts. Most of what I did were bits and pieces I picked up here and there. Unfortunately, I think I did more harm than good. One of the first major mistakes I made was using rel=”canonical” on our course overview pages and linking back to our core curriculum pages. I didn’t realize at the time that I was creating a situation where our course overview pages were not being indexed. Oops. Make sure you aren’t using rel=”canonical” on category pages and linking to featured articles or vice versa. Otherwise, you’ll be in the same boat I was.
Finally, one of the most common mistakes made with rel=”canonical” is placing it in the body, or <body> of your page. Rel=”canonical” always needs to go in the <head> section of your page, and as a best practice, as early as possible in the <head>.
That was a lot of information, so let’s rehash. To summarize:
- Rel=”canonical” should be used on pages where a large portion of content present on that page is duplicate content.
- If you’re trying to tag a paginated series, use rel=next or rel=prev instead of rel=”canonical”.
- Use absolute URLs for your canonical links and make sure that the canonical tag is only on the pages you want it on and it only shows up once.
- Do not use rel=”canonical” on category or landing pages to link to a featured page or article.
- Put the rel=”canonical” tag in the <head> of your page.
Get it? Good, now get to canonicalizing! Or don’t. Just do it right or don’t do it at all!
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