What is a canonical URL?
A canonical URL is the search engine-friendly URL that you want the search engines to treat as the most authoritative URL for that web page content. It is also the URL you want people to see in the search results.
For example, if I search for “Bell” using Google.ca, I see results for Bell telephone with www.bell.ca shown as the URL, but when I click on the search engine listing, the page I end up on is actually http://www.bell.ca/home/.
If a website has identical content that is accessible through multiple URLs (e.g. www.bell.ca, bell.ca, www.bell.ca/home, bell.ca/home), using canonical URL tags in the HTML coding gives more control over which URL is returned in search results. In this example with Bell Canada, www.bell.ca is the canonical URL – it’s the address that shows up in the search results, both paid and organic. Clicking on the search result link brings you to the lengthier www.bell.ca/home address, so Bell is probably using a permanent 301 redirect from www.bell.ca to www.bell.ca/home.
Same content, different addresses
When a search engine like Google or Bing indexes your company’s website to add it to their vast database of web pages, they might come across several different URLs for the same content. How does this happen?
Well, for example, let’s say your website’s home page is
but it also can be seen online as
without the www prefix, or as
and so on.
With these multiple URLs, the search engine algorithms will look at all these variations as duplicate content across multiple pages, and when someone conducts a search that might result in calling up one of these pages, the search engine will pick one of these URLs to display and disregard the rest. They might pick the page that you would prefer them to pick, but they might not.
How To Use Canonical Link Tags
To help the search engines index the page that you want them to recognize as the version to display, use canonical link tags on the duplicate content pages.
Using the example above, let’s decide that www.my-wonderful-company.com is the preferred URL. You would then place canonical link tags on the other URL versions of the page. This gives the search engines a “strong hint” that a different URL points to the authoritative version of this content.
For example, on the my-wonderful-company.com/index.html page you would place a canonical link tag, inside the tags, like this:
With that link code in place, a search engine would come across my-wonderful-company.com/index.html and understand that it should be indexing www.my-wonderful-company.com as the authoritative address for that content.
• Use the canonical link tag on each of the duplicate content URL pages.
• Place the canonical link tag between the tags.
You can read more about canonical URLs on Google’s Webmaster Central Blog, and of course if you any questions about canonical URLs, please leave a comment below.
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