What is RFID?

Radio Frequency Identification (RFID) is a technology whereby a reader can wirelessly query one or more uniquely identifiable tags.
Typically, the reader transmits a signal and listens for a tag-modified echo. The differences between the transmitted and received signal encode information from the tag. Tags that are in the range of the reader can be requested to provide encoded information, one example of which is an EPC (see below).