RFID tags consist of two primary components; a microchip that processes and stores the information/data and an antenna to receive and transmit RFID radio-wave signals. To read information from the tag/label, a two-way radio-receiver called an interrogator (or reader) sends a radio-wave signal to the tag(s) using its antenna. Tags that are within range of the interrogator's signal will respond with the data stored in its memory. Most RFID tags are passive tags, which use the energy from the interrogator's signal to relay its stored information. Alternatively, battery-powered RFID tags use the energy stored in its embedded battery to relay the information.
RFID tags, labels and cards fulfill the same general purpose as barcodes — that is, they store identifying information that must be scanned by a specialized reader — but RFID tags have a few distinct advantages over barcodes.
RFID tags can be read from substantially further distances than barcodes (~ 20 feet for some tags)
The relative angle at which an RFID tag is read by the reader doesn't affect the accuracy of the data
RFID tags are typically more resilient to various environmental factors
Despite the advantages of RFID, barcodes still have their place — they provide an inexpensive way of accomplishing the same purpose with minimal disadvantages.