An RFID chip that contains a unique number for identifying animals. It is embedded under the skin or attached to the animal via an ear tag. In the 1990s, the technology became popular in zoos, but in 2001, the VeriChip was the first commercial chip for people (see
VeriChip). Although the VeriChip was not popular, as of 2022, it is estimated that at least 50,000 people worldwide have some form of RFID chip implanted under their skin for identification purposes. See
RFID and
NFC.