Dealing with Canonical URL issues
Sometimes a web site is accessible via the www and the non-www version of the domain i.e. http://domain.co.uk/ and http://www.domain.co.uk/. While this is good for usability, Google will see these as 2 different pages and therefore duplicate in content. Duplicate content can have a negative impact on rankings.
To remedy this you can place a 301 Permanent Redirect from the non-www version of the domain to the www version. Detailed instructions on how to do this can be viewed here: http://www.stepforth.com/resources/web-marketing-knowledgebase/non-www-redirect.
You can also login in to Google Webmaster Tools and set your preferred display URL to the full www version.
