Everything You Wanted To Know About Rel=Canonical
Big search engines such as Google and Yahoo first started supporting the rel=canonical tag in Feb 2009. In simple terms, it may be defined as a tag that is used by Google and other search engines to identify duplicate pages on a website for the search index. Many websites have some duplicate pages for some reasons, but search engines do not like duplicate pages, and this tag is a way to get rid of that problem.
If there are duplicate pages on your website, a simple line with this tag can be included in a webpage pointing to another page.
As far as using this tag is concerned, it is extremely easy. You need to put the following HTML on the top of the HEAD element of the web page that is not canonical pointing to a page that is canonical.
<link rel=”canonical” href=”Canonical page URL”>
This tag can also be set on non-HTML pages such as PDF and other such pages by using .htaccess or PHP.
As mentioned above, this tag is used by search engines to determine the master page. There are some misconceptions associated with the use of this tag. One of most common misconceptions is that this tag leads to the redirection of the page to the canonical version similar to the 301 redirect. However, that’s not true. This tag is only useful for search engines, but it does not result in any redirection of the page at the server level or affects the display. It is a hint to the search engines, and it is not essential for search engines to honor it though all the big search engines do honor this tag.
This tag should be used on all the duplicate pages, but it should be used only when two pages are same. In case two pages are similar, but they are not identical, it’s better to make changes to one of the pages to make them different instead of using this tag. However, it’s also an established practice to mark two pages as canonical even when they are not identical.
Do not make the mistake of pointing all the pages to the homepage. Some people make this mistake and pay the price. In most cases, it is right to use the tag on websites that generate dynamic URLs. It is also right to be used on various e-commerce websites as tens of different URLs can be generated from a single page by changing the filter criteria. Similarly, it is also great for syndicated content where publishers using someone else’s content may include this tag on their website with the pages pointing to the original document.
There are many cases in which using the 301 or 302 redirect makes much more sense than using this tag. Therefore, this tag should be used carefully to make sure that search engines have the right pages of your website in their index. In case you do not use it responsibly, it may hurt the ranking of your website in the search engine result pages.
If you’re still confused about the rel=canonical, then we recommend contacting a true expert on the subject: the Dallas SEO Geek.