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Understanding canonical domains and canonical tags

Learn what canonical domains and tags are, how B12 uses them, and how they help with duplicate content issues.

Ronnel DG

Written by: Ronnel DG

Last updated: 10 Sep., 2025

Canonical tags play an important role in search engine optimization (SEO) and help prevent problems caused by duplicate content. These meta tags tell search engines which version of a page should be treated as the primary one. Only the primary version of a page should appear in search engine results.

What is a canonical domain or URL?

A canonical domain/URL is the version of your website address that search engines recognize as the main one.

For example:

  • https://www.mybusiness.com (with www)

  • https://mybusiness.com (without www)

Both URLs might point to the same site, but search engines could see them as separate unless a canonical tag is used.

What is a canonical tag?

A canonical tag is a small piece of invisible HTML code added to a webpage. It tells search engines which URL is the preferred version of that page.

Example of a canonical tag:

<link rel="canonical" href="https://www.mybusiness.com/page" />

When Google and other search engines see this tag, they know to treat the specified URL as the primary source of the content.

How B12 uses canonical tags

B12 automatically adds canonical tags to every page of your website. You don’t need to configure them manually.

  • Your primary domain is treated as the canonical version by default. This typically includes www, unless you are using a different subdomain.

  • Canonical tags are automatically included in every page’s HTML without extra work from you.

How canonical tags help with duplicate content

Duplicate content happens when the same page or similar pages appear under multiple URLs. This can confuse search engines and hurt rankings.

Canonical tags solve this problem by:

  • Consolidating SEO value across duplicates into one preferred URL.

  • Preventing search engines from indexing multiple versions of the same content.

  • Making sure your content isn’t mistakenly flagged as a duplicate.

How canonical tags differ from redirects

Canonical tags and redirects can both help solve issues with duplicate content, but they work differently:

Redirects

  • 301 redirects permanently send both users and search engines to a new page URL automatically. The redirected URL will no longer be available and will be removed from search engine results automatically.
  • Within B12, you can set up redirects for individual pages that have moved, but you cannot set up redirects for an entire domain. If you prefer to use a redirect for an entire domain (often called domain forwarding), check with your domain provider to see if they offer this feature. 

Canonical tags

  • Canonical tags keep multiple versions of a page accessible but tell search engines which version is the main one. All page URLs are available to visit independently. 

  • Non-canonical pages will not appear in search engine results, even though they can still be visited.

When to use redirects vs. canonical tags

Since redirects point all traffic to the same page URL, they may be preferable to canonical tags for consistency, overall visitor experience, and/or link authority or "link juice."

Canonical tags effectively solve problems with duplicate content if a redirect is not able to be used. Since B12 can't create domain forwarding rules, we automatically implement canonical tags.