URL canonicalization is the process of choosing the best URL when there are several options available, to avoid duplicate content issues. This is often an issue when there are multiple ways to access the same content on a website, such as through different URLs or through the use of query parameters. Canonicalization helps search engines understand which version of a page should be indexed and displayed to users.
For example, consider a website that sells clothing. The homepage might be accessible through several different URLs, such as “example.com”, “www.example.com“, and “example.com/index.html”. Without canonicalization, search engines might index all three versions of the homepage as separate pages, which can lead to issues with duplicate content. By implementing canonicalization, the website owner can specify which version of the homepage should be considered the “main” or “canonical” version, and which versions should be considered duplicate content.
There are several ways to implement canonicalization, including the use of the “rel=canonical” link element and the use of HTTP headers.
The most common method of canonicalization is to use the “rel=canonical” link element. This is a simple HTML link element that can be added to the head of a webpage. The “rel=canonical” attribute specifies the URL of the preferred or “canonical” version of the page. For example, the code below specifies that “example.com” is the preferred version of the homepage:
<link rel="canonical" href="https://example.com/" />
Another way of implementing canonicalization is by using HTTP headers. This method involves sending a “Link” header with the “rel=canonical” attribute in the HTTP response. For example, the code below specifies that “example.com” is the preferred version of the homepage:
Link: <https://example.com/>; rel=canonical
It’s important to note that both of these methods tell the search engines which version should be considered the canonical version of the page, but it does not redirect the user or the search engine crawler to the specified URL. It simply tells the search engines that this is the preferred version of the page.
Another important aspect is handling the query parameters. Query parameters are often used to control the behavior of a webpage, such as sorting or filtering content. However, they can also lead to multiple URLs accessing the same content. To address this issue, the website owner can specify which query parameters should be ignored when determining the canonical version of a page, or even better use it in the URL as a way to show the query parameters do not affect the content.
Lastly, it’s worth mentioning that there is no hard and fast rule for implementing canonicalization. There is no penalty for not implementing it but if you don’t do it then you’re missing out on some SEO benefits. It all depends on your specific use case and the structure of your website. It’s recommended that website owners take the time to evaluate their website’s URL structure and implement canonicalization as needed.
In summary, URL canonicalization is a technique used to help search engines understand which version of a webpage should be considered the “main” or “canonical” version. This can be done by using the “rel=canonical” link element or HTTP headers, and specifying which query parameters should be ignored. While there is no penalty for not implementing canonicalization, it can help to improve a website’s search engine optimization by avoiding issues with duplicate content.
Also read: Change Post URL Without Losing Traffic