We can now add NFC to the numerous methods of wireless communication. Wireless connections - whether Wi-Fi, Bluetooth or cell phones - are all based on radio signals transmitted through the air. They differ only in frequency (pitch) and amplitude (strength). The amplitude determines how far the signals can be detected - cell phones a few miles from the tower and Wi-Fi a couple of hundred feet from a home router.
Devices are tuned to certain frequencies so a radio will receive a specific station and not broadcast the microwave signals from the kitchen, the x-rays from the hospital down the street or the cosmic rays created during the big bang 15 billion years ago. I'm not making this up.
NFC stands for Near Field Communication. These are very weak (low amplitude) signals that will be used to communicate between your cell phone and billing devices that will replace credit card scanners. The NFC standard dictates the range of transmission to be four centimeters. When NFC enabled phones come out this year, they will replace credit cards in locations that can pick up the signals. Wave your cell phone near a reader and a charge will be recorded. The short transmission distance means you will not likely buy a shiny new BMW just by walking by the dealership.