Canonical Link Element - Duplicate Content
After coming across the canonical link element in February i hadn’t yet found a use for this tag / element. But now i believe i have. Basically it is designed to tell Google which page is the true version of potentially a wide range of domain combination or DB queries. For example Google could potentially see the following as different pages (this is important within SEO):
domain.com
domain.com/
domain.com/index.php
domain.com/default.asp
www.domain.com
www.domain.com/index.php
www.domain.com/default.asp
www.domain.com/
You get the basic idea….
So i here you ask how do i let Google know which page is the correct version, well before you start doing any crazy 301 re-direct’s or use the canonical link element, if possible you should be consistent from the start meaning:
• Always link to the same domain
• Use a .htaccess re-write your domain
• Set up the correct domain in Webmaster Tools
• Consistent Internal Linking
If you have followed these simple steps you will have no need to use the canonical link element, however if you free you potentially have duplicate content issues with you CMS or ecommerce platform all you need to do is add the following code in your <head></head> tags.
<link rel=”canonical” rel=”http://www.yourdomain.com” />
Google will trust that you have used this correctly and unless you have made a mistake i.e. created a infinite loop. It will assume that this command is correct. This tag is only based for sites that you fear may have duplicate content issue, any other issues can be solved with 301 re-directs.
Remember also that you can only use the canonical element internally and sub domains, NOT external websites.
References:
http://googlewebmastercentral.blogspot.com/2009/02/canonical-link-element-presentation.html
