The anatomy of an ad call can be simple, or it can be an intricate process, a sort of dance between servers to deliver the right ad for the right price.

Let’s say that you were on the Internet one evening looking to buy a new laptop. You browsed some websites, searched for laptops and studied a few, even put one in your cart at Amazon. But you got distracted before you finished a purchase and went to sleep. The next day, you wake up to check the news and notice that there is an ad from Amazon among the headlines on the website. This ad shows you laptops and maybe even the exact same laptop you had abandoned in your cart. How did this happen? How did Amazon know you would be at this website and manage to buy an ad space there showing you the exact same laptop you had been looking at just a few hours ago? It goes a little something like this