what counts as a “pageview”

Question

My main index.html page consists of 2 parts (it is written in html & jquery/javascript):

1. a fixed header that is always at the top of the page
2. a content page that is loaded when a user clicks a button (ie click "blog" and the "content" div tag gets loaded w/ the blog contents. Click "about" and the "content" div tag gets loaded w/ the about us page. When the user clicks a button on the page, the index.html and header do NOT reload; only the "content" div tag on index.html refreshes with new info.

I am using CPM advertising. This may sound like an obvious question but because the user stays on "index.html" and doesn't explicitly navigate to a "blog.html" page nor a "about.html" page, will that hurt my advertising revenue? Or, are the ad networks (buysellads.com, etc) smart enough to figure out that the user IS loading new content implicitly?

EDIT: The ad would be w/in the fixed header portion, not in the "content" part

Answer 1

If you're loading pages seamlessly (with AJAX, for example) and the Ads are placed in the part of the page that isn't reloaded (the header), that would only count as one impression. If you place the ad in the part of the page that changes, that would result in the desired behavior.

Basically, an impression is counted each time the Javascript for an ad is loaded. One load = one impression.