A web user views a DFA ad offering free ring tones.
The DFA ad server reads the user's DoubleClick cookie. If there is no cookie, a new one is created. For information about how DoubleClick uses cookies and how users can opt out of the DoubleClick ad-serving cookie, see DoubleClick's DoubleClick cookies.
Later that same day, the user visits the advertiser's website, which contains a registration form that the user has to fill out before accessing the free ring tones.
To count how many users view the form, the advertiser has put a Floodlight tag on the webpage. The tag requests an invisible 1x1-pixel image from a DFA ad server, which enables the server to detect and count the page view. As part of this process, the ad server checks the user's DoubleClick cookie to see whether the user has previously viewed or clicked on the advertiser's ad. In this case, the page view is counted as a post-impression activity