I've given a brief explaination of canonical links as from your question, about all I get is that you want to understand how to use them...
The canonical link is an HTML element you put in the <head>
section of a particular webpage as part of an SEO effort.
It tells search engines what link to use to refer to the page if multiple different links all point to the same page.
For example:
If page.html
can be reached from the following URL's
- www.domain.com/page.html
- www.domain.com/page.html?order=asc
- page.domain.com
You may want to set a canonical link in the header to ensure that only one of these is sent back to the search engine for SEO purposes
<html>
<head>
<link rel="canonical" href="http://www.domain.com/page.html" />
</head>
</html>
However, it should be noted that this is a hint and not a directive and so web spiders from search engines will not necessarily follow the link guidance.