Field programming refers to the process of placing data on an RFID tag after the manufacturing process has been completed.
Field programming is usually performed by the end user, before the tag is installed on the product or object. Obviously, the tag must have the appropriate circuitry to write the information it receives in the field onto its memory. Such tags typically have some form of non-volatile memory; "non-volatile" means that the memory chip retains information without having to use electricity to power the chip. Some field-programmable RFID tags have two forms of memory; a programmable chip and a form of read-only memory containing a unique serial number imposed at the factory.