Tiny radio frequency identification (RFID) computer chips with the needles used to implant them under the skin sit next to a dime for scale.
You've probably never seen an RFID tag, but chances are there's one within 10 ft. of you. An RFID tag--it stands for radio-frequency identification--is a tiny device consisting of a very small chip attached to a very small antenna. The chip is no great shakes, but it doesn't have to be; it just stores one very large number. When the RFID tag hears a particular radio signal, it responds by broadcasting back the number in its chip. That's its entire purpose in life. Some prototype RFID tags are about the size of a grain of ground pepper.
They don't do much,...
