Greg Grothaus is a software engineer at Google. I think I will listen to Greg closer than I would to marketing and SEO people on the web.
Very few people understand what "duplicate content" means. I include myself in that crowd. But I will learn more now. No more futtsing around. (Is futtsing a word? If not officially, it is now) Watch this video from Greg Grothaus carefully. Note the difference of intent. If the intent is to spam, to manipulate Google, you will be spanked by a decrease in your ranking as opposed to being overlooked for a search.
What I take away from this is just to do my best to offer Google's customers, the people who search, a nice experience when they get to my page. Like this one.
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