Don't use rel="canonical" as a bandaid solution

There has been some recent discussion in the SEO community about whether Google and Bing have different rules for the use of the rel=”canonical” tag. Google has said it is fine to have self-referential canonical tags (ie. the rel=”canonical” tag specifies the same URL as the page you are on), whereas Bing indicates they’d prefer the canonical tag be left blank in that case.

The proper use of rel=”canonical” can be confusing at best, and can produce devastating results at worst. So what is an SEO to do?

First of all, realize that using rel=”canonical” isn’t necessary in many cases of duplicate content. The canonical tag is a great tool for extreme situations and enterprise-level sites, but on small to medium sized websites there are often other solutions.

Choose Non-WWW to WWW, or Vice Versa

A lot of canonical issues arise because a website is available at both the WWW and non-WWW versions of the domain, and other sites may end up linking to either version. Using your favorite method, redirect the non-WWW to the WWW, or vice versa. If you do this when the site is initially built, you can eliminate most instances of the wrong version being linked to (people tend to just grab whatever URL is in the address bar, anyway). Make the choice early on, and stick with it.

Don’t Use URL Parameters

If possible, try to avoid using parameters in URLs.

• If you run an e-commerce or community-based site, store all session information in a cookie rather than as parameters. This is a programming best practice to ensure users don’t get access to each others’ information.
• Avoid specifying sort order or viewing options of a search results or product page in the URL. It is better to display the page with a static URL, and make use of AJAX for sorting and filtering.
• If you use tracking parameters for referrals, replace the question mark (?) in the URL with a hashtag (#). Don’t forget to adjust your Google Analytics tracking code to allow hashtags!

Don’t Generate URLs on the Fly

Some content management systems generate page URLs on the fly, based on how the user navigated to it. I suppose the idea behind it is that the URL then becomes sort of a breadcrumb trail so the user can easily figure out how get to higher levels, but this is just a bad idea on so many levels.

Ideally, you want each product, article, post or resource to be available at a single, static URL, regardless of how the user got there.

301 Redirects

No matter how hard you try to avoid it, you sometimes end up with pages on your site being linked to in strange ways, potentially causing duplicate content issues. In cases like this, you may want to set up redirect rules that specify certain parameters (or all parameters, if you want to be extreme) get redirected back to the root page. If it only occurs on a few pages across your site, you can individually redirect them to the preferred URL (an advantage small sites have over enterprise ones).

In general, you should try to prevent duplicate content issues before they happen, or fix them when they do. Use of the rel=”canonical” tag is advanced and shouldn’t be applied as a blanket solution to all canonicalization problems.

Photo: Jason Tester/Flickr

The canonical tag is simply a way to silence webmasters.

Yesterday at SMX West it was announced that Google, Yahoo! and Live have agreed upon a method to help webmasters define original content within a site. The canonical tag is a meta tag used to tell search engines which page to list in SERPs when multiple listings of the same, or very similar content exist in their databases.

On-site duplicate content has been a big issue since the beginning of the web. There are lots of things that could cause search engine spiders to index the same content at multiple locations. URL canonical variations (http://www.exmaple.com vs. http://example.com) is the most common issues, but there are others. This is a good explanation of the canonical tag and how it’s implemented.

In september the Google Webmaster Central Blog published a fairly extensive post on how search engines handle on-site duplicate content in hopes of dispelling a lot of the rumors and speculation circling the issue. Despite how clear the article was, and all the other resources on the web, there were still LOTS of questions about the issue.

As new webmasters come into the space trying to understand SEO and mitigating duplicate content the easy thing to do is ask Google. If you’re site is set up correctly duplicate content shouldn’t be an issue. The canonical tag, is not the end-all be-all of duplicate content. You still need a sitemap, good URLs, redirection from the www or the non-www to the correct path, etc. This tag is simply an easy answer to the duplicate content question.

What do you think? Have you implimented the canonical tag yet? Is it really THAT important considering all the other things that still need to be done?