For the uninitiated, rel=canonical is a special tag placed in the head section of your HTML page. It relates to duplicate content and provides a strong hint to search engines about which content on your website is the ‘master copy’ so to say. For example, if you have a mobile website on a subdomain, you would want to use the rel=canonical tag to tell search engines that it has similar content to your main website. Without using the tag, the authority of your page is split (which is a bad thing).
Easy to Make Rel=Canonical Mistakes
However, properly implementing the rel=canonical tag can be confusing even for a seasoned SEO company. That’s because you wouldn’t know until much later if you have made a mistake. Here are the common rel=canonical mistakes listed in the article:
Mistake 1: rel=canonical to the first page of a paginated series
Mistake 2: Absolute URLs mistakenly written as relative URLs
Mistake 3: Unintended or multiple declarations of rel=canonical
Mistake 4: Category or landing page specifies rel=canonical to a featured article
Mistake 5: rel=canonical in the body tags
This is a must-read article for any webmaster or budding SEO. Head over to the Google Webmaster Central blog to find out more.