Radio-frequency identification (RFID) is an auto-identification technology similar to other common auto-ID technologies such as bar codes or magnetic strips. A physical object is associated with a unique identifying number (UID) that is incorporated in an RFID transponder, or “tag.” The tag is usually attached to a physical object, such as a carton, a pallet, or a container filled with a product. An RFID reader (interrogator) extracts the UID from the tag.