Saturday 16 July 2011

Canonical Error in Website SEO

It’s difficult enough to say, let alone understand; getting your head around canonical issues is a must if your website optimisation is to yield the results you desperately seek.

In SEO and website design terms, Canonicalization exists where you have more than one URL address for the same page. For instance:

abc.com
www.abc.com
www.abc.com/index.html

All three of these URLs will be pointing to your homepage, which means that the search engines will view these as different pages, indexing each page and allowing them to compete against one another. What’s the issue you might say, well the problem is that this generates duplicate content in the Google search engine results (SERP’s), which Google heavily penalises; which in turn means that your pages will likely be pulled from the search engine results, or will be pushed back in the SERP’s, leaving your site out in the cold.

You should use at the very least either a rel=canonical tag, or appropriate 301 redirects, however we recommend using both of these methods.
Why is duplicate content bad for SEO?
Search engines aim to provide the most relevant content to a search query, so when they come across two pages which are exactly the same they are forced to choose one over the other, as displaying both would represent a flaw in their service. Sometimes choosing one is not realistic or possible and so a penalty is placed on the website or page in question. This is obviously an issue for SEO as duplicate content will inevitably lead to some of your pages disappearing from the index.
Define your canonical URL

The rel=canonical tag allows you to dictate which URL the search engines should consider the ‘master copy’, the one you wish all SEO benefits to revert to. The rel=canonical tag is placed in the HTML header text similar to the meta description and meta keywords tags:

<meta name="description" content="Site Description/>
<meta name="keywords" content="Site Keywords" />
<link rel="canonical" href="http://www.abc.com/" />

It is important to understand that this simply informs the search engine bots of your preference, but it does not actually redirect the content, thus a human will be able to see the content via the canonical urls if you do not force a redirect. This can sometimes lead to links being developed to urls that you do not want indexed.
So what is a 301 redirect?

A 301 redirect is a permanent redirect, allowing you to move one URL to another automatically, so for example if you try going to http://abc.com it will automatically redirect you to the proper url which is http://www.abc.com.

A 301 redirect should be done from the webserver and not in code. Setting up a redirect is relatively easy but often done incorrectly.  It is imperative that the ‘status code’ sent to the search engine bots upon redirection is a 301, not a 302 or any other code.

Can I still just use a 301 redirect?

Yes you can, in fact the safest way to deal with the canonical issue is to have appropriate 301 redirects in place for your website.

However the reason we recommend having both is because some search engine bots will actually look for the rel=canonical tag now, so having it there deals with the issue quickly and in the way they are looking for it to be dealt with. If a search engine does not look for the rel=canonical tag then at least you have the redirect to fall back on. Most importantly if you 301 redirect properly then no one will be able to see your content under any other url than the one you choose.

You should understand that there are many search engines on the Internet and not all are as sophisticated as Google, so it is safe to assume that not all search engines are sophisticated enough to work with rel=canonical tag, so by not 301 redirecting your url’s properly you run the risk of other search engines issuing duplicate content penalties and the like.
This and many other website optimisation factors are essential for successful websites. At Designer Websites we will ensure your new website is properly 301 redirected and contains the appropriate canonical tags, as well as dealing with many other technical SEO factors.

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