2006 was the first year I remember paid blog posts appearing from content farms that would exist only to increase your inbound links and page rank. Those days companies were paying cents per post to get their sites to #1 in Google while Google just wagged their finger and said "naughty, naughty."

It's a shame, because Page Rank was a smart idea.

Around 2011 to 2012 after the first of many updates with names like hurricanes came and washed away the good.