There are a million ways you might see this page, but only one web address indexed in Google search results thanks to the wonderful Canonical Tag, a meta tag used to suggest which version of a page should be included in a search index.
Other working versions of this very page may include:
- http://wiideman.com/canonical-tags (no www prefix)
- https://www.wiideman.com/canonical-tags (no trailing slash)
- https://www.wiideman.com/canonical-tags/?utm_campaign=Newsletter (tracking)
- https://www.wiideman.com/canonical-tags/?really-anything-here (whatever)
By placing the tag below in the code of this page (within the <HEAD>, we’re sending a signal to Google and other search engines that we’re aware of duplicate content issues and would prefer they only recognize one version of the page (as opposed to penalizing the page with the Google Panda smackdown).
<link rel="canonical" href="https://www.wiideman.com/technical-seo/canonical-tags/" />
Other common reasons canonical tags become a must, include:
- Product variations that do not use custom titles or descriptions
- Certain paginated categories (page 1, page 2, page 3)
- Printer-friendly view of a page
- Mobile URLs
- Latitude and longitude caused by embedded maps
When Canonical Tags Shouldn’t Be Used
You must be thinking, “why not use canonical URLs on ALL pages?”. Excellent question!
According to our friends at Webmaster Central, there are several common mistakes with using the canonical tag, such as:
- Different languages – instead use rel=”alternate”
- The page contains a noindex robots meta tag or is blocked in robots.txt
- Using more than one instance of tag – results in all being ignored
- Canonicalizing a series of paginated pages (not categories)
- Typos and misplacement are also common mistakes to look out for
How to Test
We use Deepcrawl.co.uk for efficient crawling of every URL, allowing us to analyze pages where plugins, such as the one we use on this website, don’t automatically add the canonical tag for us.