Rand Fishkin once called the canonical url tag "the most important advancement in SEO practices since sitemaps". With its most recent release Business Catalyst is fighting duplicate content again. Canonical url tag selections are now activated for products in all BC e-commerce sites.
The canonical link helps prevent duplicate content issues by specifying (to search engines) the preferred version of a web page. It helps consolidate PageRank and avoids various issues with search engines.
It looks like this:
<link rel="canonical" href=" http://bc.com/catalog/product ">
Let՚s say you have a product called "widget", and it is assigned to four catalogs. As a result your product will render on four separate pages (with the same content):
When someone searches for your widget using their favorite search engine, how will the search engine know which page to show? Remember, the urls all contain the same content. The search engine does its best to index and rank these pages in a way to only show one, but your site will likely suffer from having duplicate content.
This is where the canonical url tag comes in. Using this tag, you get to tell the search engines which url to use for ranking. "It’s similar to a 301 redirect in terms of transferring link references and other effects to the canonical form of the page."
Maybe nothing. Fortunately Business Catalyst does most of the work for you. If your product only has one catalog, there’s no action for you to take. If you have multiple catalogs assigned to the product, Business Catalyst will select the first product URL to use in the canonical tag. If you don't like the url BC chooses, you can easily change it using a dropdown in the product’s settings (or using the import feature).
BC automatically adds the canonical url tag to a product page that is NOT selected in the product՚s admin settings. If the page visited is the preferred page (selected in dropdown), there is no need for BC to add the canonical url tag.
If you're unsure of which to choose as the preferred url, I suggest doing some research on how well each page is performing. Using Google Webmaster Tools you can find out lots of valuable data on all of your product pages (ranking, click-thru rate, etc). A simple strategy is to choose the page performing the best. This will consolidate the pagerank of all of the other pages (with duplicate content) to your best performing page.
Scott is the founder of Thrise LLC, a Business Catalyst partner advisory board member, an Adobe Community Professional, a BC Sandpile manager, an Adobe Certified Expert, an Adobe User Group Manager, a Google AdWords Certified Partner, and a full-time astronaut. Scott has had his hands in HTML since the 90’s and often presents on topics related to design and marketing.