The use of integrated circuit cards in payment applications started in France for telephone cards and withdrawal cards from automated tellers. This chapter analyses the security of smart cards in payment applications. It provides an overview of the different types of integrated circuit cards in terms of memory and processing power, operating systems, and their interfaces with personal computers. The chapter describes the International Organization for Standardization standards of integrated circuit cards with contacts and contactless are summarized. It presents the main items in an integrated circuit cards as well as their interfaces to personal computers. Traditional prepaid telephone cards are contact cards, monoapplication and disposable. The total value of telephone units corresponds to an equal number of memory cells. Radiofrequency identification (RFID) technology uses the same physical principles of contactless integrated circuit cards to track objects. An RFID contactless system consists of a transponder or tag, an antenna, a reader/writer, and a host computes.