Every now and again I have this problem: I see an ad for a product I’m interested in on a web page just at the same time that I click on a button or link to take me to the next page. I click the back button to go back and see the ad, but the ads are regenerated and the ad that I saw isn’t there any more. Designers who are serious about maximising sales should avoid this happening to their users. When you click back you should see what you saw last time.