Resumen
The payment is only a part of the shopping activity. To be useful, payment protocols must be complemented by methods to choose services that are to be delivered and by ways to charge for those services. The range of the possible charging methods lies between two extremes. The first, flat rate, means that the buyer's charges do not depend on usage of the offered services. The advantage of flat rate is its simplicity, the disadvantage is that heavy users are charged the same as the occasional ones. The second method, which is analogous to bean counting, is to produce an accounting record for each delivered data packet. The advantage of bean counting is its accuracy, its disadvantage is that the charging may become more costly to implement than the service that is offered. There is a business opportunity in providing charging and billing as a service for companies that sell information. Two kinds of companies may benefit from such service. An example of the first is Interactive Investor, which provides financial data for a high monthly fee and wants to move down-market.