Hi! Its canonical not chronicle . If site open without www or with www , you have to redirect in a http://www manner .
Google can reach to your web page through different URLs, this may create a confusion of duplicate content for search engine. To avoid this, we choose a preferred path for the web page or say canonical path for the web page. If you don’t set a preferred path this may raise canonical issues.
Hi, Search Engines employ URL canonicalization in order to assign importance to web pages and to reduce indexing of duplicate pages. Thus, Canonical issue is the term used for the search engines to avoid the confusion of the duplicate content as Google visit your site with different URL'S (with xyz.com and www.xyz.com). If you do not take care about this it will raise canonical issue, which falls under duplicate content.
I am yet to see anyone explaining the canonical URL in the right sense and so let me explain. Canonical url is not about www and non-www but it is about having different url for the same content like for example http://www.go4expert.com/forumdisplay.php?f=93 And http://www.go4expert.com/forumdisplay.php?f=93&page=1 For example on a multi page layout you can have the same content when you add extra parameter like page=1 or things like those and though both are valid url's they contain the same information and this is canonical issues where parameters like sort or page numbers makes url as different but have the same content.
