My question is - Do the advertisers have a setting that allows them to show only ads that reach a certain amount per click? Or is there software there that blocks ads that fall below a certain amount per click?
Just wondering why my impressions would fall so drastically - when my ad, my keywords, and my ranking have all stayed the same?
Those appropriate websites that advertise your ad are called the content network. Each time your ad shows up on a content page when someone is viewing it - Google records that as an impression. You pay when someone sees that impression and clicks on your ad. That is how they come up with the Click thru rate or CTR = clicks/impressions. I beleive that's how it works anyway.