Imagine going to the store to look for a new fall jacket. You go to the rack and find one you like. You try it on. It fits and you decide to take it. So you zip it up, toss your old jacket in the trash, and walk out the front door of the store.
If you did this now, you might expect to get stopped by store security. In the not-so-distant future, however, stores might use a technology that would allow them to tag the jacket to be read automatically by a scanner as you walked out of the store. And you might have signed up for a service with the store and your bank to allow your account to be automatically debited. It's certainly not an impossible scenario; the technology to do this is already here (it's actually been around for decades). It's called RFID, and it stands for Radio Frequency Identification.
You may already be familiar with a form of RFID that is already in widespread use: the pet chip. A pet chip is a form of RFID that can be embedded under the skin of your dog or cat by your local veterinarian. The RFID contains a small ID number for your pet, which is linked to a database that has your ownership information. Vets and animal shelters have scanners that can be used to detect the presence of the chip. So if your poor pooch gets lost and picked up by others, they can take him to a vet, the vet can scan Rover and look up your information, and get him home to you safe and sound.
What Are RFIDs, Anyway?
Radio Frequency IDs are essentially microchips that are attached to antennas. The microchip contains a very small amount of stored information, usually no more than 1K–2K, which can be transmitted back to the scanner.
There are two broad categories of RFIDs: active and passive. Active RFIDs are about the size of a coin and hold more information than the passive RFIDs. They also have a tiny battery that provides them with the power to transmit information. Because they are self-powered and store more information, they are also more costly. The RFIDs are capable of receiving and storing information, they can have a range as much as 50–75 feet, and the batteries can supply power for several years. Active RFIDs might be used to track large shipping containers, the kind that can go from boat to rail to truck without being opened. In this application, RFIDs could identify contents, shipper, destination, and so on.
Passive RFIDs don't contain any power source. Instead, they use the signal sent out from the scanner itself to power the microchip circuit to transmit back the information stored in the RFID. Because they don't contain any power source, they have a more limited range—from a few inches to a few feet. Passive RFIDs can be read-only, or read-write, but they can't generally store as much info as active RFIDs. The advantage of passive RFIDs, however, is that they are less costly and can be incredibly small, as small as 1/64-inch and thinner than a sheet of paper.