Near field communication (NFC) is a standard for exchanging data wirelessly by two nearby (a few inches) portable devices.
The idea behind NFC is to allow two people to share data from their portable devices. These might be smartphones, Web Tablets, or even eBook readers. The data could be anything from exchanging business card data to a book. Communication is also possible between an NFC device and an unpowered NFC chip, called a "tag".
The NFC standards are based on another standard called RFID (Radio Frequency ID) used in credit cards and passports but much more general purpose. It provides bi-directional wireless communication capabilities between nearby devices and is much less complex than Wi-Fi. It is, however, a low bandwidth capability only suitable for small amounts of data transfer.
Android uses an offshoot called Android Beam. It uses NFC to establish a temporary Bluetooth connection between devices, allows the transfer of data and then breaks the connection. Another variant, by Samsung, uses NFC to establish a temporary WiFi Direct connection and then disables it after the transfer. WiFi Direct has a higher transfer rate than Bluetooth. This permits the rapid transfer of larger amounts of data such as a photo or eBook.
Other potential uses include credit card transfers. The new Apple Pay feature uses NFC to do the transfer.
 For more information
- http://en.wikipedia.org/wiki/Near_Field_Communication Wikipedia
- http://www.gsmworld.com/ GSM (Global System for Mobile Communications)