The Internet demand experiment, or INDEX, is a market and technology trial. Its objective is to determine how much users value different qualities of service for Internet access. Findings from the trial imply that today's system of flat-rate pricing by ISPs is very inefficient. Flat-rate pricing wastes resources, requires light users to subsidize heavy users, and hinders deployment of broadband access. INDEX is a prototype of an alternative ISP model that offers differentiated quality service on demand, with prices that reflect resource cost. In this alternative ISP consumers pay less, suppliers increase profits, and the deployment of broadband access is facilitated.