Prevent Duplicate Content By Blocking Archives From Search Engines

Hi,
Why would you want to block archive pages anyway? The answer is to prevent Google from penalizing your blog due to duplicate content. You see archive pages do not have contents of their own. What you see on them are duplicates, taken from individual post pages. And if both pages (the individual post and archive pages having the same content) are indexed by Google, that constitutes duplicate content.

That’s exactly the case for this blog –duplicate content due to archive pages. And I paid the price for it during the last Google PageRank update. This blog’s PR went down from 4 to 3.

The problem probably started when I added Blogger Archive widget to the sidebar. This widget provided access for web crawlers to the archive pages, which eventually led to the pages being indexed by Google.

Preventing duplicate content
You can prevent duplicate content by telling search engines not to index archive pages. This can be achieved by adding a “noindex” robots meta tag to the archive pages (and archive pages only).