I was working on a client's newly relaunched site recently when I ran into a potential duplicate content issue. Specifically, the client's site had incorporated an additional version of content specially formatted for printing. This version included a "no index, no follow" meta tag. Seems like the correct thing to do, right? Wrong.
Why No Index, No Follow Is The Wrong Choice
No Index, No Follow is an appropriate meta tag to use when: a) you want to prevent search engine indexing of a Web page and b) you want to prevent the links on a page from being followed by the search engine robots. Because the page isn't indexed by engines, any link "juice" from inbound links from other websites that point to the print-formatted version pages is essentially lost forever. But there's a better way...
The Canonical Tag Is a Better Choice
In the case of duplicate content, canonical tags are nearly always (if not always) the better choice. Launched two years ago by Google, the canonical tag allows you to tell search engines, including both Google and Bing, which page you prefer to rank for the given content. The real beauty, though, of the canonical tag, is that that it passes the "link juice" from the duplicate version to the preferred page version.
In the case of my client, the canonical tag would have been a better choice for the print-formatted page versions. Why? Unfortunately, the current "No Index, No Follow" meta simply sends engines the message not to index that information on that page or follow the links on that page, so it can act as a brick wall to a search engine robot when it is indexing the site. The canonical tag, however, communicates to the engine robots to instead rank a different version of the page. Also, if anyone links to the print-formatted version, the link juice would be passed to the preferred page instead of being lost completely with "No Index, No Follow."
Duplicate Content - It's More Common Than You Might Think
Don't think you're at risk for duplicate content? Here's a list of common situations where I regularly find duplicate site content when examining website structure:
So examine your site(s) and consider using the canonical tag for your duplicate content issues. It's often a better option for duplicate content issues, retaining more innate value than the "No Index, No Follow" meta tag.