Near field communications (NFC) is the exchange of information between two devices via wireless signal. For example, a wireless signal emitting from your cell phone can act as a credit card when making a purchase. In the case of a mobile wallet application, those devices would be a mobile phone and a point-of-sale device at a checkout counter.
http://robertsiciliano.com/blog/2013/11/23/nfc-app-on-androids-facilitates-automation/