A canonical tag within a URL is set to reference another internal URL, signifying that the original URL is effectively 'canonicalized' to the other.
Why is this important?
When Page A is canonicalized to Page B, Page B is identified as the preferred version to search engines. This suggests to search engines that Page B should be regarded as the primary page of the two, often resulting in Page A being omitted from search indexes, while Page B inherits any backlinks originally pointed to Page A.
It's critical to distinguish that a canonical tag serves as a guide rather than a directive, which means search engines might disregard it if it seems inappropriate. You can refer to how Google explains canonical tags for handling repetitive content.
What does the Optimization check?
The Optimization is activated by any internal URL that has a canonical link tag (via HTML or HTTP header) pointing to a different internal URL within the same subdomain.
Examples that trigger this Optimization
Take for instance the URL: https://example.com/page-x
This Optimization would activate if the URL includes:
A canonical link in the <head> pointing to an internal URL:
<link rel="canonical" href="https://example.com/page-y" />
Or a canonical link specified in the HTTP Header pointing to an internal URL:
HTTP/... 200 OK...Link: <https://example.com/page-y>; rel="canonical"
And for the URL: https://example.com/page-x?color=blue
This Optimization would also activate if the referenced canonical URL was the standard version of the URL, or any other internal URL:
A canonical link in the <head> to the standard URL:
<link rel="canonical" href="https://example.com/page-x" />
Or a canonical link via HTTP Header pointing to the standard URL:
HTTP/... 200 OK...Link: <https://example.com/page-x>; rel="canonical"
Why is this Optimization marked 'Insight'?
Labeled as an 'Insight', this Optimization suggests an area for exploration without immediate need for action. It is designed to draw attention to canonicalization for further review, ensuring the canonical links are implemented as intended.
Although canonical tags can be verified for appropriateness, it is beyond the system's capacity to determine definitively whether Page B is indeed the preferred canonical version of Page A.