Google, Yahoo and MSN Make SEO for Duplicate Content Easier
SEO has just been made a bit easier with an agreement between the Big 3 to accept a canonical link reference. This canonical link reference serves as an indication of a website’s original source of content so that harmful or ambiguous interpretations of a website’s internally linked duplicate content can be avoided.
Search engine optimisation (SEO) specialists and webmasters have been haunted for years with the prospect of being unnecessarily penalized for duplicate content, or having their unique page dubbed as unworthy of anything but a listing in a supplemental index. Search engine optimisation theories and duplicate content strategies have been steeped in controversy, and the mysteries of patented algorithms on duplicate content remains. However the mist surrounding the question of how to deal with necessary internal duplicate content has parted. Google, Yahoo and MSN have made search engine optimisation a little easier by agreeing to a canonical linking standard for duplicate content.
Website development and website usability often require duplicate content in urls that are used to shape and define products and categories, identify session and tracking ids and provide separate urls for print page formatting. Robots.txt, nofollows and 301s are programming elements that can help manage duplicate content issues, however there are advantages and disadvantages to each, and none are a “one size fits all” answer to duplicate content. Search engine optimisation specialists and website owners must also consider the ramifications of unethical scraping and link backs, the passing on of “link juice” from internal or external webpages, and blatant copyright violations.
However, for internal linking purposes, the Big 3 search engines - Google, Yahoo and MSN - have agreed that the following code may be used to identify the appropriate “primary” (or canonical) webpage that the spiders should apply the metrics of the duplicate canonical-coded page to:
When the canonical link attribute is applied to a webpage, the search engine algorithmic analyzers will then credit the referred canonical URL with any link juice or other metrics of search engine optimisation that contribute to page rank - such as trust, domain age, or authority - in the same way a 301 redirect would. However, the canonical url tag attribute for search engine optimisation is different than a 301 direct because only the search engine spider is redirected, and not the website visitor. The search engines do suggest that canonical urls are to be used within a single domain, and 301s should still be used across multiple domains.
The canonical url tag for search engine optimisation is part of the HTML Header and is placed similarly as the Title tag and Meta tags. Google, Yahoo and MSN have all stated that absolute and relative urls are allowed, however Yahoo specifically stated that absolute links are preferred. MSN stated that a canonical link will be treated as a “hint” to the bots, however Google stated it will be treated as a “strong hint.”
The tag attribute of the canonical link for search engine optimisation is new as of February, 2009. Webmasters and search engine optimisation specialists as well as the search engines themselves will be defining and redefining the force and effect of canonical links for search engine optimisation. Each search engine will handle the canonical link for search engine optimisation according to their current uniquely patented algorithms, thus the canonical tag attribute will contribute differently to each search engine’s search engine result pages (SERPS).
Search engine optimisation consultants working with duplicate content are long overdue for concrete directives to establish the webmaster’s original intent when using duplicate website content. Search engines and websites both serve the user. Tag attributes such as the new canonical link for search engine optimisation help search engines interpret duplicate content, and helps website owners direct their webpages to users through the SERPS. By following solid search engine directives such as the canonical link tag, website owners can work to qualify themselves to place in the SERPS with the help of the search engines themselves.