First, advertisers only pay if you click the on the ad.,/quote>
This is not true. Web advertising has three models, which are often used in combination:
1: Referral fee. When an ad leads to a sale, the ad hoster gets a cut.
2: Click-throughs. When an ad is clicked, the ad hoster gets a fee.
3: Impressions. When an ad is displayed, the ad hoster gets a smaller fee.
Paying for impressions is an important part of ad business - it's similar to billboard and magazine ads, in that the user don't click them, but hopefully remembers - if nothing else subconsciously, so the next time they're at the store they pick the goods with the logo and color combinations that's been impressed on them.