Canonical URL Tag

[marknorman]

I have 3 websites with same content, I want to add Canonical tag to my main website. Is this also important to mentioned other duplicate URL in canonical tag in main website? or just need to just add

[AlanMosley]

Just

why do you have 3 websites with same content?

what are you trying to achieve?

Are they on different tlds, .for example .co.uk .com.au

[marknorman]

Actually my website is old, and I never used canonical tags, Some of the websites copied my content and they added canonical tag on there website. How google find that my website is original content source. ?

[AlanMosley]

They may already know this.

It is my understanding that pinching someone's content and putting a canonical tag on it does little. if you were to put a canonical tag on your site pointing to theirs then that would be a signal that they are the original content owners.

having a page domain.com with a canonical tag pointing to domain.com does nothing,

having 2 pages domainB.com and domainA.com one with a canonical tag pointing to the other tells the search engine the other is the one to give credit to.
If you don't have access to the other sites, a canonical on your own site is not going to do you much good.

[MoosaHemani]

Agreed with Alan, do as Alan said and Google will actually figure out what is the original version of the website.