Radio frequency identification, or RFID, is a generic term for technologies that use radio waves to automatically identify people or objects. There are several methods of identification, but the most common is to store a serial number that identifies a person or object, and perhaps other information, on a microchip that is attached to an antenna (the chip and the antenna together are called an RFID transponder or an RFID tag). The antenna enables the chip to transmit the identification information to a reader. The reader converts the radio waves reflected back from the RFID tag into digital information that can then be passed on to computers that can make use of it.

An RFID system consists of a tag, which is made up of a microchip with an antenna, and an interrogator or reader with an antenna. The reader sends out electromagnetic waves. The tag antenna is tuned to receive these waves. A passive RFID tag draws power from field created by the reader and uses it to power the microchip’s circuits. The chip then modulates the waves that the tag sends back to the reader and the reader converts the new waves into digital data

RFID is not necessarily "better" than bar codes. The two are different technologies and have different applications, which sometimes overlap. The big difference between the two is bar codes are line-of-sight technology. That is, a scanner has to "see" the bar code to read it, which means people usually have to orient the bar code towards a scanner for it to be read. Radio frequency identification, by contrast, doesn’t require line of sight. RFID tags can be read as long as they are within range of a reader. Bar codes have other shortcomings as well. If a label is ripped, soiled or falls off, there is no way to scan the item. And standard bar codes identify only the manufacturer and product, not the unique item. The bar code on one milk carton is the same as every other, making it impossible to identify which one might pass its expiration date first.

Just as your radio tunes in to different frequency to hear different channels, RFID tags and readers have to be tuned to the same frequency to communicate. RFID systems use many different frequencies, but generally the most common are low- (around 125 KHz), high- (13.56 MHz) and ultra-high frequency, or UHF (850-900 MHz). Microwave (2.45 GHz) is also used in some applications. Radio waves behave differently at different frequency, so you have to choose the right frequency for the right application.

Different frequencies have different characteristics that make them more useful for different applications. For instance, low-frequency tags are cheaper than ultra high frequency (UHF) tags, use less power and are better able to penetrate non-metallic substances. They are ideal for scanning objects with high-water content, such as fruit, at close range. UHF frequencies typically offer better range and can transfer data faster. But they use more power and are less likely to pass through materials. And because they tend to be more "directed," they require a clear path between the tag and reader. UHF tags might be better for scanning boxes of goods as they pass through a bay door into a warehouse. It is probably best to work with a consultant, integrator or vendor that can help you choose the right frequency for your application.

A microchip’s sole function is to store a unique ID number that is used to retrieve a pet parent’s contact information—it differs from a GPS, which is used for tracking, and requires a power source such as a battery.

• When a microchip scanner is passed over the skin of a microchipped pet, the implanted microchip emits an RF (radio frequency) signal. The scanner reads the microchip’s unique ID code. The microchip registry is called, and the registry company uses the ID number to retrieve the pet parent’s contact information from the pet recovery database.

A: It won’t hurt any more than a routine vaccination – having a microchip implanted doesn’t even require anesthetic. The procedure is performed at your veterinarian’s office and is simple and similar to administering a vaccine or a routine shot.

The microchip comes preloaded in a sterile applicator and is injected under the loose skin between the shoulder blades. The process takes only a few seconds, and your pet will not react any more than he would to a vaccination.

A: A microchip will normally last the lifetime of your pet because it is composed of biocompatible materials that will not degenerate over time.

Microchips carry only a unique identification number.

If your pet gets lost and is taken to a vet clinic or animal shelter, your pet will be scanned for a microchip to reveal his unique ID number. That number will be called into the pet recovery service, and you will be contacted using the contact information on file with your pet’s microchip.

**It is vital to keep your contact information up to date so that you can be reached.