In a nutshell a canonical is used to tell Google where you got the content from originally.
Imagine you had to do an essay, and when you handed that long 2000 word essay in – most of the work was Jeff’s. The tutor would mark you down nearly 100% and tell you off. this is the same as Google telling you off. It sees your web page and also an identical one somewhere else, be it on your own site or another website and so instead of arguing who was the real author it will ignore both pages and you will not get any points for it. So you might have not written it anyway.
Cheating does not pay!
Imagine you had to do an essay, and when you handed that long 2000 word essay in – most of the work was Jeff’s. The tutor would mark you down nearly 100% and tell you off. this is the same as Google telling you off. It sees your web page and also an identical one somewhere else, be it on your own site or another website and so instead of arguing who was the real author it will ignore both pages and you will not get any points for it. So you might have not written it anyway.
Cheating does not pay!