RFID stands for Radio Frequency Identification.
In the most basic scenario, a reader connects to an antenna which sends a radio signal across a narrow band of radio spectrum. This radio signal communicates with a tag to identify the product the tag is attached to. This tag information can be used for identification or other solution activities. Antenna and tag selection will vary based on solution environment and need.
No, commercial RFID applications are under FCC Guidelines which incorporate safety standards for human exposure.
Among other advantages RFID does not require a direct line of sight, enables multiple reads simultaneously and has built-in serialization.
RFID and Barcodes can completely replace or compliment BarCode systems. The EPC (UHF RFID) encoding standard is based on the existing UPC system.
Our friend Justin Patton, Auburn University RFID Lab Director explains RFID below