Radio Frequency IDentification (RFID) is a system used to track objects, people, or animals using tags that respond to radio waves. RFID tags are integrated circuits that include a small antenna. The are typically small enough that they are not easily noticeable and therefore can be placed on many types of objects. This technology is most often used in the credit card industry, with RFID chips embedded in credit cards for secure transactions. RFID is similar to Near Field Communication (NFC), which is used to link devices together to send data back and forth such as photos or videos; allowing for a full two-way communication. RFID is different in the way that it is only “read only”, which means that that information sent from your credit card to the card reader is a one-way communication, the reader cannot communicate back to the credit card, it can only read what the card sent it.
Source: TechTerms
Additional Reading: RFID: How The Digitization of Retail is Progressing
Related Terms: Near Field Communication (NFC)