What is Canonical URL in SEO?

Canonical URL defined as the preferred URL for the page content to be indexed in the Major Search Engines. Canonical URL is used by the Major Search Engines like Google, Yahoo, Bing, etc. Many websites have two or more links of the same content with different parameter. In this time Search Engines are confused about Which One is needed to be Index?

To help illustrate this point, let’s say each of the following URLs is a means to access the homepage of your site:

• http://www.yoursite.com/
• http://yoursite.com/
• http://www.yoursite.com
• http://yoursite.com
• http://www.yoursite.com/index.html
• http://yoursite.com/index.html

While the average person may recognize these URLs as the same, from a technical search engine standpoint, they are not. A web server sees these six unique URLs as six unique pages. If they’re all crawlable, they’ll all be indexed.

In most cases, however, different content doesn’t exist on each of these variations, and without Google “canonicalizing” a URL, or selecting one URL best representative of the set to return in results, all could very easily be viewed as duplicated content by the engines. This is bad. To make sure the search engines are indexing the correct page, you need to select which variation of the URL you’ll want to set as canonical.

Once we’ve determined which URL we want to set as canonical, it’s time to start building up that authority. The first thing we’ll need to do is make sure that every single variation of the URL is redirected to the canonical by way of a 301 Redirect.

Next, make sure you’ve specified the Canonical URL tag in your HTML header. This is another way to tell the search engines what the canonical URL of any given page on our site should be.

The Canonical Tag would look like this:

On our homepage, it’s quite simple really:

<link rel="canonical" href="http://yoursite.com/" />

Same goes for directories and pages on your domain as well:

<link rel="canonical" href="http://yoursite.com/directory/ " />

<link rel="canonical" href="http://yoursite.com/directory/page" />

And of course, whenever you modify URLs, make sure you’re properly redirecting the old addresses with 301s.

As you establish canonical URLs across your site, you need to remember that your internal links are one of the most important canonical signals. It is critical that all of your links are pointing to the URLs that you’ve labeled as canonical in the head tags. Otherwise, you’re giving the search engines mixed messages which could cost you rankings.