Sometimes people also refer to NFC as RFID, which is a similar older technology. RFID stands for radio frequency identification and both NFC and RFID employ radio signals for tagging all sorts of objects. NFC is a newer technology, which includes the same, read and write feature of RFID but has two more functions, which involve card emulation and P2P (peer-to-peer) communication. In this chapter, we will focus on the read and write function. The tags and the card show in Figure 6.1 have a small memory of 1K where a unique number is stored. The wonderful part of NFC/RFID technology is that the tags and cards do not need any batteries to work. These tags and cards are powered from the signal of the receiver, which gives them enough "juice" to broadcast the information stored in the memory. This is why these tags and cards can't be read if they are further away than 10 cm from the receiver. The electromagnetic field simply can't travel that far. But still, this gives the technology...