First of all, I admit that I don't know just as much I should know about canonical URLs. All I know is that Google wants to know which URL is the best representative of the content, if there are several URLs that point to one page. [Ex. www.xenforo.com vs xenforo.com ] While investigating the possible causes of traffic drop on our website, I found the following in Google webmaster tools - Note that the 'Not Selected' count has grown up way beyond what it should have been. Look at the beginning of the lines though- 1. We switched from vB -> XF on December 2011. This is where the 'Not Selected' count is a little above the 'total indexed' count. 2. Sometime between April & May, the count goes up by huge margin! I believe this is the time when we installed the tag-interlinking plugin on our wordpress setup (but not sure). I wish to know from XF webmasters - 1. Do you see similar trend in your GWT (especially those who've converted from vB or other boards) and setup 301 redirects. 2. How does Xenforo handle canonical URLs? 3. If you have 'Not Selected' more than 'Total Indexed' - what are the places to look for in Xenforo? I'm going to look at WordPress, but I want to be absolutely sure that there's nothing to worry about on the XF front. I'll be thankful to everyone who reads and responds to this post.