Microchip Identification is technically referred to as Radio Frequency Identification or  RFID.  It is a method of identification which has two parts:  1)  A microchip, also known as a transponder, tag or chip and  2)  A scanner or reader that sends a signal to the microchip.

The chip is small enough to be injected under the skin of even the most fragile of pets or birds.  The same chip is used in horses where it is placed into the nuchal ligament.  Safe and permanent, the tiny rice-sized microchip remains for the life of the animal.  The chip is designed with an extended operating life and requires no care.

The information about the animal and or the owner is not on the chip itself, but is kept in a database or registry and is "pulled up" when correlated to the chip number.  That is why microchip numbers must be unique.  One number, one animal.  The database contains information regarding the animal, the owner or care giver, the veterinarian and any contact phone numbers supplied by the owner or care giver.  This data must be accessed to reunite a lost pet with its family. It must also be accessed in cases of natural disaster when owners, animals and veterinarians have been separated.

While RFID can be used to identify almost anything from car keys to designer handbags, the type of microchip used for animals is special.  It must be able to withstand fluids and be small enough to be delivered via standard injection.  It has no battery and no power source and can therefore not be used as a GPS device.

A microchip system works when the scanner sends a signal to the microchip.  That signal is then “bounced” back to the scanner where the chip number is displayed.  This transmission occurs at a specific radio frequency. To be truly effective, accurate and fast, scanners and microchips must operate at the same frequency.

Microchips (from any manufacturer) that are introduced into the system are said to be 'compatible' when they operate at the frequency emitted by the scanners most predominately in use. Scanners and chips should operate at matching frequencies, with matching technical protocols.

This critical factor is why in 2006, Congress sent a proposed rule change to force an incompatible pet microchip frequency to the USDA for further study.  The USDA after public hearings in six major pet recovery cites released its Report in the summer of 2007.

Various frequencies and protocols for RFID exist around the world. They include but are not limited to 125kHz (kilohertz), 128kHz, 134.2kHz, 400kHz, 3.56mHz and 2.54gHz.   It has been demonstrated in the field and through research that when scanners are designed to read or detect more than one frequency, there will be loss in efficiency of the scan and an increase in the time it takes to detect a chip.

In the United States of America, 98% of microchipped companion animals carry the 125 kHz frequency. It has been the standard of care since 1996 when microchip manufacturers and animal care groups came together to standardize equipment and operate at the same frequency.