For example, think about how the Internet has affected pricing. From the mostly fixed pricing practices of the past century, the Internet seems to be taking us back into a new age of fluid pricing. The flexibility of the Internet allows Web sellers to instantly and constantly adjust prices on a wide range of goods based on demand dynamics. In other cases, customers control pricing by bidding on auction sites such as eBay or negotiating on sites such as Price-line. Still other companies customize their offers based on the characteristics and behaviors of specific customers.