We’ve frequently spoken about Canonical Issues and the impact they have on your website but I thought I’d go into a little bit more detail about what a Canonical issue is, a few of the different types of canonical issue and how you can resolve these on your website.

A Canonical issue on a website is where there are a number of methods of viewing the content on a page, for example the homepage of your website.  There are a number of ways you might find a canonical issue on the homepage of your website, some example URLs are below:

www.yourdomain.co.uk

http://yourdomain.co.uk

www.yourdomain.co.uk/index.html

www.yourdomain.co.uk/default.aspx

All of these pages could refer to the homepage of your website and if they all load (without the address in the address bar changing) then you could be creating duplicate content in showing these different URLs.

The www. non www. canonical issue (www.yourdomain.co.uk and http://yourdomain.co.uk) can be resolved from your domain registration control panel, by ensuring that the non www. version (http://yourdomain.co.uk) is redirected using a 301 to www.yourdomain.co.uk.  Adding a canonical tag to the homepage with the correct URL to resolve this.

When you have set up the redirect from the non www. domain name to the correct www. domain name you need to ensure that this is working for all of the pages on your website and that http://yourdomain.co.uk/products/ redirects to www.yourdomain.co.uk/products/ so that all of the sub pages on the site aren’t also being duplicated in the same way the homepage was.

Adding this canonical tag to the homepage also goes some way to resolve the issues created where a homepage can be viewed as a named page.  However, you still need to ensure that all of the internal links on the site to the homepage go to www.yourdomain.co.uk and not www.yourdomain.co.uk/index.html or www.yourdomain.co.uk/default.aspx.  It is also a good idea to include a 301 redirect from these named pages to the homepage of your website.

Making sure you don’t have duplicate content via one of the above canonical issues is an important part of the SEO work you will do on your website and something that is an important step towards creating authority for your website in the search engines.