Canonical in SEO

The Canonical tag in a Search Engine Optimization is all about duplicate content and preferred content. Helping search engines identify which is the original page in relation to duplicated content.

There are many legitimate reasons for duplicate content, particularly when it comes to system-generated URLs. These include:

  1. Multiple URLs – particularly on eCommerce sites where URLs are created through filter options for price, color, rating, etc.
  2. HTTP, HTTPS & WWW-search engines see http://www.mydomain.com, http://mydomain.com, and https://www.mydomain.com as distinct pages, and will crawl (and possibly index) them as such.
  3. Mobile URL: when using a special URL (typically m.mydomain.com) for the mobile version of your website.
  4. Country URL – when using multiple country-specific URLs, the content largely remains the same, with only a few minor differences. This does not apply if the language is different, in which case you want the search engines to return separate results.

True duplication is when the particular content appears on multiple unique URLs (www.mydomain.com versus www.someotherdomain.co), often as a result of content syndication. Also, remember to follow the guidelines while performing migration from HTTP to HTTPS.

The Process of Canonicalization

For example, you have two version of the same pages with same contents google will not come to know which one is original and which one is a duplicate.

Two pages are

  • http://example.com/wordpress/seo-plugin/
  • http://example.com/wordpress/plugins/seo

You pick one of your two pages as the canonical version. It should be the version you think is the most important one.

Canonical Tag Syntax is as follows:

<link rel=”canonical” href=”http://example.com/wordpress/seo-plugin/”>