Abstract: The system for the automatic determination of customized prices and promotions automatically constructs product offers tailored to individual shoppers, or types of shopper, in a way that attempts to maximize the vendor's profits. These offers are represented digitally. They are communicated either to the vendor, who may act on them as desired, or to an on-line computer shopping system that directly makes such offers to shoppers. Largely by tracking the behavior of shoppers, the system accumulates extensive profiles of the shoppers and the offers that they consider. The system can then select, present, price, and promote goods and services in ways that are tailored to an individual consumer. Likely shoppers can be identified, then enticed with the most effective visual and textual advertisements; deals can be offered to them, either on-line or off-line; detailed product information screens can be subtly rearranged from one type of shopper to the next.