What is Canonical URL ...?

[cookies186]

Hi,

What does Canonical URL mean?

Will Canonical URL has any effect on multiple URL's? If so, what is it use for SEO purpose?

[yinji]

http://www.xx.com/xx.html such as this url is canonical URL
if ?,!,*,&,in url,then the url is not canonical url

[myndconsulting]

Yes, it does have [ mainly positive if used properly ] effect on multiple URLs that point to one and the same place.
Imagine you have:
somedomain.com
somedomain.com/index.php
somedomain.com/index.php?page=home
etc.
And all these are meant to point at one and the same location, then you should implement a rel="canonical" pointing to just one of them as a choice.