fdc5e7d5_Robots_txt_Tutorial__3
[0] link rel=nofollow [1] destination page only crawled if linked to from other documents [2] destination page only appears if linked to from other documents [4] If you are doing something borderline spammy and are using nofollow on internal links to sculpt PageRank then you look more like an SEO and are more likely to be penalized by a Google engineer for "search spam" [5] link text [3] 
Using this may waste some PageRank. It is recommended to use on user generated content areas.
Robots.txt Tutorial
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