Canonical URL is the website page that is considered the main page among all its duplicates. The website owner chooses which version of the page to consider canonical to indicate to the search bot which one should be indexed and to ignore the rest. To choose a canonical URL, the website owner needs to specify the rel="canonical" tag in the HEAD section of the HTML code of the page. If this is not done, the search engine will decide which URL to consider canonical on its own. It is also possible that the system will consider several addresses canonical, which will lead to negative consequences for the website.
It is extremely important to specify canonical URLs for multi-page websites, where there may be pages that lead to several different addresses or where there are pages with slight differences. For example, in an online store, you can get to a product page using different filter combinations, which will change the final URL. On the product page itself, you can switch between product modifications, such as changing the color of a T-shirt. The content of the pages will hardly differ, so it is necessary to indicate which of these versions is considered canonical.
Canonical URL performs several functions at once:
- helps to achieve the indexing of necessary pages;
- allows you to choose the page that the website owner wants to display in organic search;
- promotes SEO promotion;
- facilitates the collection of statistics for website pages.
After choosing a canonical URL, the search bot will scan duplicate pages much less frequently and they will not be ranked by the search engine. It will be easier for the search bot to understand which page is the most relevant of all and to index it. The rel="canonical" tag is not only necessary to use for pages that have full duplicates. Even if the content of the pages differs slightly, it is recommended to specify a canonical URL to avoid confusion.
To find out which pages of the website are considered canonical, you can use Google Search Console. Even if the owner did not specify the rel="canonical" tag, the search engine can choose canonical URLs on its own. The system can also choose a canonical page at its discretion, even if the tag is specified for a different URL. rel="canonical" is just one of the markers that signal the search bot about the canonical URL. In addition to it, the system takes into account the protocol, page content, and the presence of the address in the sitemap.
