Moz reporting appropriate Canonical tag usage but no canonical tag on page !?

[Dan-Lawrence]

I take it this means that the page in question has been referenced via a different pages canonical tag but that the page in question itself does not have a self referencing canonical tag (and that it should do)

cheers

dan

[FedeEinhorn]

Exactly, although it was "invented" to prevent duplicate content issues and therefore used on those pages that are duplicates, it doesn't make any harm (and possibly bring benefits for future issues that may arise), you should still use it.

As it says, it is a recommendation, not a must :).

[Dan-Lawrence]

i thought they were supposed to be , see mozon page grader advice:

Although the canonical URL tag is generally thought of as a way to solve duplicate content problems, it can be extremely wise to use it on every (unique) page of a site to help prevent any query strings, session IDs, scraped versions, licensing deals or future developments to potentially create a secondary version and pull link juice or other metrics away from the original. We believe the canonical URL tag is a best practice to help prevent future problems, even if nothing is specifically duplicate/problematic today.

Recommendation: Add a canonical URL tag referencing this URL to the header of the page.

[FedeEinhorn]

Although canonical tags are not intended to point to themselves, I mean the page http://www.domain.com/page shouldn't have a canonical tag pointing to itself: "http://www.domain.com/page" I found it very useful. Specially now that sources add their own query string (ie http://www.domain.com/page?utm_source=twitter), to minimize the chances of having a duplicate content issue.