The embedded chip is usually attached to a contact pad which has a pattern of eight metallic segments on its surface (conforming to international standards) for VCC (power supply voltage), RST (used to reset the microprocessor of the smart card), CLK (clock signal), GND (ground), VPP (programming or write voltage), and I/O (serial input/output line). Two segments are reserved for future use (RFU). When the card is inserted into a reader, corresponding contacts in the reader come into contact with these metallic segments to provide power to the card and a means of communicating with it