NFC stands for "Near-Field Communication". It is a form of wireless communication between two devices, which has a very short range (usually less than 10cm) and can transmit simple information between the two devices.

In most day-to-day applications, the communication comprises an "initiator", which is powered, and a "target", which is a passive circuit. The initiator provides an electromagnetic field, from which the target derives some power and responds. 

In the case of WiZ NFC tags, the initiator is your phone, and the target is the WiZ NFC tag you may have attached to your coffee table. This design allows for small NFC tags that do not require batteries to operate. Just make sure you don't stick them onto metallic surfaces, since that could create disturbances in the communication.