Comment on Duplicate Content and Canonical URLs by SEO Dave.
For those with posts/pages with a lot of comments (like this Page you are reading now, over 200 comments) you have to spread them over Paged Comments (a core WordPress setting). This Page currently has 10 Paged Comments.
There are SEO negatives and benefits to this setup, since I use the Stallion SEO Super Comments feature many of the comments generate a Post like page with the comments content and they need at least one link to be indexed and the Paged Comments are indexed by Google etc… so they supply those links. Having Paged Comments means the comment content you and your visitors generate can be ‘archived’ over multiple Paged comments pages, like I said this one is broken over 10 pages, these can potentially generate their own traffic.
Bad news is at the top of all the Paged comments is the entire contents of the main post which is a potential duplicate content issue, for this Page you are on now it’s not such a problem since I only added a couple of lines of text, so the 10 Paged Comments are 95% unique content (it’s almost all my and my visitors comment text), but for most scenarios that can be a lot of content duplicated over and over again: I have a jokes site with jokes with thousands of comments split over a 100+ paged comments pages each with the entire jokes contents copied over and over again (far from ideal!). What’s also bad SEO news the title elements (title tags) are all the same, so on my jokes site I have hundreds of indexed paged comments with the same title tag, again far from SEO ideal (ideal is all pages have unique title tags).
You’ll find many SEOs and WordPress SEO Plugin developers advise noindexing the paged comments (or not using them if you don’t have too many comments). The All In One SEO Plugin for example adds a canonical URL to the main post on all Paged Comments pages so only the main post is indexed. I don’t like this option and the next release of Stallion (Stallion 8) has solved this issue.
1st The paged comments pages (pages 2, 3, 4 etc…) can be set to show an excerpt of the main post so only the main post loads the entire posts content: the paged comments are a bit like comment archives with a snippet of the original post and the majority of the content being unique comments.
2nd If you set the Stallion All In One SEO Title Tag and the four Stallion Keyphrases (part of the Post/Pages edit page) they along with the original post title will be used as the title tag for the paged comments pages.
Main Post/Page uses the Stallion All In One Title Tag.
Paged Comment 1, 7, 13 and 19 uses the Stallion Related Keyphrase 1.
Paged Comment 2, 8, 14 and 20 uses the Stallion Related Keyphrase 2.
Paged Comment 3, 9, 15 and 21 uses the Stallion Related Keyphrase 3.
Paged Comment 4, 10, 16 and 22 uses the Stallion Related Keyphrase 4.
Paged Comment 5, 11, 17 and 23 uses the Original Post Title.
Paged Comment 6, 12, 18 and 24+ uses the Stallion All In One Title Tag.
This means as long as the Stallion Keyphrases etc… are set the paged comments will have unique title tags and have the potential to gain those SERPs. I’ll probably use the same format for the anchor text of the link back to the main post as well. Part of Stallion 8 is a lot more use of the keyphrases in widgets etc… including Google Panda busting options to mix when a related keyphrase is used on a widget by page type (far, far less identical anchor text usage in Stallion 8).
I’ve also added the features from the stand alone Stallion WordPress SEO Plugin with the addition of being able to add a canonical URL to the main post/page on paged comments (if you don’t want the above paged comment features).
Lots of other stuff added like easy Google authorship, automated 404 pages 301 redirected to home, 301 redirect attachment URLs, blocking bad queries (stop hackers checking for malicious code), more SPAM bot blocking…