The electronic system of administration of cards is cheaper than the system of check clearing. The union of cards of store and nets with the credit system and debit tends to grow, for reduction of operational costs of processes and increase of the yield of the involved companies. Although the charged salty interests on the revolving credit (240% to the year), this financial system reveals efficient and until economic when its user creates the habit of the full payment of the monthly invoice, but a trap to the domestic financial health when it effects only the payment of the minimum, becoming a great snow ball. The volume of total insolvency it is around 9,8% of the total of the wallet, reason of the so high interests, but it exists offers to the times exaggerated for certain customers who have high volumes of credit in some flags, that can provoke financial problems to its users in the lack of control of the personal finances. It is clearly and inevitable to perceive that the manual money as we know tends to disappear in the time, in virtue of the increasing development of the technology. The system of credit card offers guarantees for the store or rendering borrower of services, although the crisis the volume continues increasing, guaranteeing the sales and the circulation goods and services for the economy. With projections of growth of the order of 20% to the year, the sector will be able to arrive at a financial volume of at least R$ 800 next billion in the five years, having in 2010 to pass the number of 600 million cards emitted in circulation. The industry of credit cards is promising and generates profits of order 10% 15%, but we cannot deny the praticidade of the system that took account of our lives.