Exactly right. Imagine you have a list of 10,000 people who have visited your website whom you want to target with ads. You don't want to show anybody your ad m

Exactly right. Imagine you have a list of 10,000 people who have visited your website whom you want to target with ads. You don't want to show anybody your ad more than ten times. You're using an ad network that reaches ten million people. Your ad will only appear when the trackers tell you that someone is on your target list.